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
  19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/moduleloader.h>
  22 #include <linux/elf.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/fs.h>
  25 #include <linux/string.h>
  26 #include <linux/kernel.h>
  27 #include <linux/bug.h>
  28 #include <linux/mm.h>
  29 #include <linux/gfp.h>
  30 #include <linux/jump_label.h>
  31
  32 #include <asm/page.h>
  33 #include <asm/pgtable.h>
  34
  35 #if 0
  36 #define DEBUGP(fmt, ...)                                \
  37         printk(KERN_DEBUG fmt, ##__VA_ARGS__)
  38 #else
  39 #define DEBUGP(fmt, ...)                                \
  40 do {                                                    \
  41         if (0)                                          \
  42                 printk(KERN_DEBUG fmt, ##__VA_ARGS__);  \
  43 } while (0)
  44 #endif
  45
  46 void *module_alloc(unsigned long size)
  47 {
  48         if (PAGE_ALIGN(size) > MODULES_LEN)
  49                 return NULL;
  50         return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
  51                                 GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC,
  52                                 -1, __builtin_return_address(0));
  53 }
  54
  55 #ifdef CONFIG_X86_32
  56 int apply_relocate(Elf32_Shdr *sechdrs,
  57                    const char *strtab,
  58                    unsigned int symindex,
  59                    unsigned int relsec,
  60                    struct module *me)
  61 {
  62         unsigned int i;
  63         Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
  64         Elf32_Sym *sym;
  65         uint32_t *location;
  66
  67         DEBUGP("Applying relocate section %u to %u\n",
  68                relsec, sechdrs[relsec].sh_info);
  69         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  70                 /* This is where to make the change */
  71                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  72                         + rel[i].r_offset;
  73                 /* This is the symbol it is referring to.  Note that all
  74                    undefined symbols have been resolved.  */
  75                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
  76                         + ELF32_R_SYM(rel[i].r_info);
  77
  78                 switch (ELF32_R_TYPE(rel[i].r_info)) {
  79                 case R_386_32:
  80                         /* We add the value into the location given */
  81                         *location += sym->st_value;
  82                         break;
  83                 case R_386_PC32:
  84                         /* Add the value, subtract its position */
  85                         *location += sym->st_value - (uint32_t)location;
  86                         break;
  87                 default:
  88                         pr_err("%s: Unknown relocation: %u\n",
  89                                me->name, ELF32_R_TYPE(rel[i].r_info));
  90                         return -ENOEXEC;
  91                 }
  92         }
  93         return 0;
  94 }
  95 #else /*X86_64*/
  96 int apply_relocate_add(Elf64_Shdr *sechdrs,
  97                    const char *strtab,
  98                    unsigned int symindex,
  99                    unsigned int relsec,
 100                    struct module *me)
 101 {
 102         unsigned int i;
 103         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
 104         Elf64_Sym *sym;
 105         void *loc;
 106         u64 val;
 107
 108         DEBUGP("Applying relocate section %u to %u\n",
 109                relsec, sechdrs[relsec].sh_info);
 110         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 111                 /* This is where to make the change */
 112                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 113                         + rel[i].r_offset;
 114
 115                 /* This is the symbol it is referring to.  Note that all
 116                    undefined symbols have been resolved.  */
 117                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
 118                         + ELF64_R_SYM(rel[i].r_info);
 119
 120                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
 121                        (int)ELF64_R_TYPE(rel[i].r_info),
 122                        sym->st_value, rel[i].r_addend, (u64)loc);
 123
 124                 val = sym->st_value + rel[i].r_addend;
 125
 126                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 127                 case R_X86_64_NONE:
 128                         break;
 129                 case R_X86_64_64:
 130                         *(u64 *)loc = val;
 131                         break;
 132                 case R_X86_64_32:
 133                         *(u32 *)loc = val;
 134                         if (val != *(u32 *)loc)
 135                                 goto overflow;
 136                         break;
 137                 case R_X86_64_32S:
 138                         *(s32 *)loc = val;
 139                         if ((s64)val != *(s32 *)loc)
 140                                 goto overflow;
 141                         break;
 142                 case R_X86_64_PC32:
 143                         val -= (u64)loc;
 144                         *(u32 *)loc = val;
 145 #if 0
 146                         if ((s64)val != *(s32 *)loc)
 147                                 goto overflow;
 148 #endif
 149                         break;
 150                 default:
 151                         pr_err("%s: Unknown rela relocation: %llu\n",
 152                                me->name, ELF64_R_TYPE(rel[i].r_info));
 153                         return -ENOEXEC;
 154                 }
 155         }
 156         return 0;
 157
 158 overflow:
 159         pr_err("overflow in relocation type %d val %Lx\n",
 160                (int)ELF64_R_TYPE(rel[i].r_info), val);
 161         pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
 162                me->name);
 163         return -ENOEXEC;
 164 }
 165 #endif
 166
 167 int module_finalize(const Elf_Ehdr *hdr,
 168                     const Elf_Shdr *sechdrs,
 169                     struct module *me)
 170 {
 171         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
 172                 *para = NULL;
 173         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 174
 175         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 176                 if (!strcmp(".text", secstrings + s->sh_name))
 177                         text = s;
 178                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
 179                         alt = s;
 180                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
 181                         locks = s;
 182                 if (!strcmp(".parainstructions", secstrings + s->sh_name))
 183                         para = s;
 184         }
 185
 186         if (alt) {
 187                 /* patch .altinstructions */
 188                 void *aseg = (void *)alt->sh_addr;
 189                 apply_alternatives(aseg, aseg + alt->sh_size);
 190         }
 191         if (locks && text) {
 192                 void *lseg = (void *)locks->sh_addr;
 193                 void *tseg = (void *)text->sh_addr;
 194                 alternatives_smp_module_add(me, me->name,
 195                                             lseg, lseg + locks->sh_size,
 196                                             tseg, tseg + text->sh_size);
 197         }
 198
 199         if (para) {
 200                 void *pseg = (void *)para->sh_addr;
 201                 apply_paravirt(pseg, pseg + para->sh_size);
 202         }
 203
 204         /* make jump label nops */
 205         jump_label_apply_nops(me);
 206
 207         return 0;
 208 }
 209
 210 void module_arch_cleanup(struct module *mod)
 211 {
 212         alternatives_smp_module_del(mod);
 213 }