arch/x86_64/kernel/module_64.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 #include <linux/bug.h>
  27
  28 #include <asm/system.h>
  29 #include <asm/page.h>
  30 #include <asm/pgtable.h>
  31
  32 #define DEBUGP(fmt...)
  33
  34 #ifndef CONFIG_UML
  35 void module_free(struct module *mod, void *module_region)
  36 {
  37         vfree(module_region);
  38         /* FIXME: If module_region == mod->init_region, trim exception
  39            table entries. */
  40 }
  41
  42 void *module_alloc(unsigned long size)
  43 {
  44         struct vm_struct *area;
  45
  46         if (!size)
  47                 return NULL;
  48         size = PAGE_ALIGN(size);
  49         if (size > MODULES_LEN)
  50                 return NULL;
  51
  52         area = __get_vm_area(size, VM_ALLOC, MODULES_VADDR, MODULES_END);
  53         if (!area)
  54                 return NULL;
  55
  56         return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL_EXEC);
  57 }
  58 #endif
  59
  60 /* We don't need anything special. */
  61 int module_frob_arch_sections(Elf_Ehdr *hdr,
  62                               Elf_Shdr *sechdrs,
  63                               char *secstrings,
  64                               struct module *mod)
  65 {
  66         return 0;
  67 }
  68
  69 int apply_relocate_add(Elf64_Shdr *sechdrs,
  70                    const char *strtab,
  71                    unsigned int symindex,
  72                    unsigned int relsec,
  73                    struct module *me)
  74 {
  75         unsigned int i;
  76         Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
  77         Elf64_Sym *sym;
  78         void *loc;
  79         u64 val;
  80
  81         DEBUGP("Applying relocate section %u to %u\n", relsec,
  82                sechdrs[relsec].sh_info);
  83         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
  84                 /* This is where to make the change */
  85                 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
  86                         + rel[i].r_offset;
  87
  88                 /* This is the symbol it is referring to.  Note that all
  89                    undefined symbols have been resolved.  */
  90                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
  91                         + ELF64_R_SYM(rel[i].r_info);
  92
  93                 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
  94                        (int)ELF64_R_TYPE(rel[i].r_info),
  95                        sym->st_value, rel[i].r_addend, (u64)loc);
  96
  97                 val = sym->st_value + rel[i].r_addend;
  98
  99                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 100                 case R_X86_64_NONE:
 101                         break;
 102                 case R_X86_64_64:
 103                         *(u64 *)loc = val;
 104                         break;
 105                 case R_X86_64_32:
 106                         *(u32 *)loc = val;
 107                         if (val != *(u32 *)loc)
 108                                 goto overflow;
 109                         break;
 110                 case R_X86_64_32S:
 111                         *(s32 *)loc = val;
 112                         if ((s64)val != *(s32 *)loc)
 113                                 goto overflow;
 114                         break;
 115                 case R_X86_64_PC32:
 116                         val -= (u64)loc;
 117                         *(u32 *)loc = val;
 118 #if 0
 119                         if ((s64)val != *(s32 *)loc)
 120                                 goto overflow;
 121 #endif
 122                         break;
 123                 default:
 124                         printk(KERN_ERR "module %s: Unknown rela relocation: %Lu\n",
 125                                me->name, ELF64_R_TYPE(rel[i].r_info));
 126                         return -ENOEXEC;
 127                 }
 128         }
 129         return 0;
 130
 131 overflow:
 132         printk(KERN_ERR "overflow in relocation type %d val %Lx\n",
 133                (int)ELF64_R_TYPE(rel[i].r_info), val);
 134         printk(KERN_ERR "`%s' likely not compiled with -mcmodel=kernel\n",
 135                me->name);
 136         return -ENOEXEC;
 137 }
 138
 139 int apply_relocate(Elf_Shdr *sechdrs,
 140                    const char *strtab,
 141                    unsigned int symindex,
 142                    unsigned int relsec,
 143                    struct module *me)
 144 {
 145         printk("non add relocation not supported\n");
 146         return -ENOSYS;
 147 }
 148
 149 int module_finalize(const Elf_Ehdr *hdr,
 150                     const Elf_Shdr *sechdrs,
 151                     struct module *me)
 152 {
 153         const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL;
 154         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 155
 156         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 157                 if (!strcmp(".text", secstrings + s->sh_name))
 158                         text = s;
 159                 if (!strcmp(".altinstructions", secstrings + s->sh_name))
 160                         alt = s;
 161                 if (!strcmp(".smp_locks", secstrings + s->sh_name))
 162                         locks= s;
 163         }
 164
 165         if (alt) {
 166                 /* patch .altinstructions */
 167                 void *aseg = (void *)alt->sh_addr;
 168                 apply_alternatives(aseg, aseg + alt->sh_size);
 169         }
 170         if (locks && text) {
 171                 void *lseg = (void *)locks->sh_addr;
 172                 void *tseg = (void *)text->sh_addr;
 173                 alternatives_smp_module_add(me, me->name,
 174                                             lseg, lseg + locks->sh_size,
 175                                             tseg, tseg + text->sh_size);
 176         }
 177
 178         return module_bug_finalize(hdr, sechdrs, me);
 179 }
 180
 181 void module_arch_cleanup(struct module *mod)
 182 {
 183         alternatives_smp_module_del(mod);
 184         module_bug_cleanup(mod);
 185 }