arch/x86_64/kernel/module.c

   1 /*  Kernel module help for x86-64
   2     Copyright (C) 2001 Rusty Russell.
   3     Copyright (C) 2002,2003 Andi Kleen, SuSE Labs.
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 */
  19 #include <linux/moduleloader.h>
  20 #include <linux/elf.h>
  21 #include <linux/vmalloc.h>
  22 #include <linux/fs.h>
  23 #include <linux/string.h>
  24 #include <linux/kernel.h>
  25 #include <linux/slab.h>
  26
  27 #include <asm/system.h>
  28 #include <asm/page.h>
  29 #include <asm/pgtable.h>
  30
  31 #define DEBUGP(fmt...)
  32
  33 #ifndef CONFIG_UML
  34 void module_free(struct module *mod, void *module_region)
  35 {
  36         vfree(module_region);
  37         /* FIXME: If module_region == mod->init_region, trim exception
  38            table entries. */
  39 }
  40
  41 void *module_alloc(unsigned long size)
  42 {
  43         struct vm_struct *area;
  44
  45         if (!size)
  46                 return NULL;
  47         size = PAGE_ALIGN(size);
  48         if (size > MODULES_LEN)
  49                 return NULL;
  50
  51         area = __get_vm_area(size, VM_ALLOC, MODULES_VADDR, MODULES_END);
  52         if (!area)
  53                 return NULL;
  54
  55         return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL_EXEC);
  56 }
  57 #endif
  58
  59 /* We don't need anything special. */
  60 int module_frob_arch_sections(Elf_Ehdr *hdr,
  61                               Elf_Shdr *sechdrs,
  62                               char *secstrings,
  63                               struct module *mod)
  64 {
  65         return 0;
  66 }
  67
  68 int apply_relocate_add(Elf64_Shdr *sechdrs,
  69                    const char *strtab,
  70                    unsigned int symindex,
  71                    unsigned int relsec,
  72                    struct module *me)
  73 {
  74         unsigned int i;
  75         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
  76         Elf64_Sym *sym;
  77         void *loc;
  78         u64 val;
  79
  80         DEBUGP("Applying relocate section %u to %u\n", relsec,
  81                sechdrs[relsec].sh_info);
  82         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  83                 /* This is where to make the change */
  84                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  85                         + rel[i].r_offset;
  86
  87                 /* This is the symbol it is referring to.  Note that all
  88                    undefined symbols have been resolved.  */
  89                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
  90                         + ELF64_R_SYM(rel[i].r_info);
  91
  92                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
  93                        (int)ELF64_R_TYPE(rel[i].r_info),
  94                        sym->st_value, rel[i].r_addend, (u64)loc);
  95
  96                 val = sym->st_value + rel[i].r_addend;
  97
  98                 switch (ELF64_R_TYPE(rel[i].r_info)) {
  99                 case R_X86_64_NONE:
 100                         break;
 101                 case R_X86_64_64:
 102                         *(u64 *)loc = val;
 103                         break;
 104                 case R_X86_64_32:
 105                         *(u32 *)loc = val;
 106                         if (val != *(u32 *)loc)
 107                                 goto overflow;
 108                         break;
 109                 case R_X86_64_32S:
 110                         *(s32 *)loc = val;
 111                         if ((s64)val != *(s32 *)loc)
 112                                 goto overflow;
 113                         break;
 114                 case R_X86_64_PC32:
 115                         val -= (u64)loc;
 116                         *(u32 *)loc = val;
 117 #if 0
 118                         if ((s64)val != *(s32 *)loc)
 119                                 goto overflow;
 120 #endif
 121                         break;
 122                 default:
 123                         printk(KERN_ERR "module %s: Unknown rela relocation: %Lu\n",
 124                                me->name, ELF64_R_TYPE(rel[i].r_info));
 125                         return -ENOEXEC;
 126                 }
 127         }
 128         return 0;
 129
 130 overflow:
 131         printk(KERN_ERR "overflow in relocation type %d val %Lx\n",
 132                (int)ELF64_R_TYPE(rel[i].r_info), val);
 133         printk(KERN_ERR "`%s' likely not compiled with -mcmodel=kernel\n",
 134                me->name);
 135         return -ENOEXEC;
 136 }
 137
 138 int apply_relocate(Elf_Shdr *sechdrs,
 139                    const char *strtab,
 140                    unsigned int symindex,
 141                    unsigned int relsec,
 142                    struct module *me)
 143 {
 144         printk("non add relocation not supported\n");
 145         return -ENOSYS;
 146 }
 147
 148 int module_finalize(const Elf_Ehdr *hdr,
 149                     const Elf_Shdr *sechdrs,
 150                     struct module *me)
 151 {
 152         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL;
 153         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 154
 155         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 156                 if (!strcmp(".text", secstrings + s->sh_name))
 157                         text = s;
 158                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
 159                         alt = s;
 160                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
 161                         locks= s;
 162         }
 163
 164         if (alt) {
 165                 /* patch .altinstructions */
 166                 void *aseg = (void *)alt->sh_addr;
 167                 apply_alternatives(aseg, aseg + alt->sh_size);
 168         }
 169         if (locks && text) {
 170                 void *lseg = (void *)locks->sh_addr;
 171                 void *tseg = (void *)text->sh_addr;
 172                 alternatives_smp_module_add(me, me->name,
 173                                             lseg, lseg + locks->sh_size,
 174                                             tseg, tseg + text->sh_size);
 175         }
 176         return 0;
 177 }
 178
 179 void module_arch_cleanup(struct module *mod)
 180 {
 181         alternatives_smp_module_del(mod);
 182 }