arch/mips/kernel/module.c

   1 /*
   2  *  This program is free software; you can redistribute it and/or modify
   3  *  it under the terms of the GNU General Public License as published by
   4  *  the Free Software Foundation; either version 2 of the License, or
   5  *  (at your option) any later version.
   6  *
   7  *  This program is distributed in the hope that it will be useful,
   8  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  *  GNU General Public License for more details.
  11  *
  12  *  You should have received a copy of the GNU General Public License
  13  *  along with this program; if not, write to the Free Software
  14  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  15  *
  16  *  Copyright (C) 2001 Rusty Russell.
  17  *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
  18  *  Copyright (C) 2005 Thiemo Seufer
  19  */
  20
  21 #undef DEBUG
  22
  23 #include <linux/moduleloader.h>
  24 #include <linux/elf.h>
  25 #include <linux/vmalloc.h>
  26 #include <linux/slab.h>
  27 #include <linux/fs.h>
  28 #include <linux/string.h>
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/spinlock.h>
  32
  33 struct mips_hi16 {
  34         struct mips_hi16 *next;
  35         Elf_Addr *addr;
  36         Elf_Addr value;
  37 };
  38
  39 static struct mips_hi16 *mips_hi16_list;
  40
  41 static LIST_HEAD(dbe_list);
  42 static DEFINE_SPINLOCK(dbe_lock);
  43
  44 void *module_alloc(unsigned long size)
  45 {
  46         if (size == 0)
  47                 return NULL;
  48         return vmalloc(size);
  49 }
  50
  51 /* Free memory returned from module_alloc */
  52 void module_free(struct module *mod, void *module_region)
  53 {
  54         vfree(module_region);
  55         /* FIXME: If module_region == mod->init_region, trim exception
  56            table entries. */
  57 }
  58
  59 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
  60                               char *secstrings, struct module *mod)
  61 {
  62         return 0;
  63 }
  64
  65 static int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v)
  66 {
  67         return 0;
  68 }
  69
  70 static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v)
  71 {
  72         *location += v;
  73
  74         return 0;
  75 }
  76
  77 static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
  78 {
  79         *location = v;
  80
  81         return 0;
  82 }
  83
  84 static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v)
  85 {
  86         if (v % 4) {
  87                 printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
  88                 return -ENOEXEC;
  89         }
  90
  91         if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
  92                 printk(KERN_ERR
  93                        "module %s: relocation overflow\n",
  94                        me->name);
  95                 return -ENOEXEC;
  96         }
  97
  98         *location = (*location & ~0x03ffffff) |
  99                     ((*location + (v >> 2)) & 0x03ffffff);
 100
 101         return 0;
 102 }
 103
 104 static int apply_r_mips_26_rela(struct module *me, u32 *location, Elf_Addr v)
 105 {
 106         if (v % 4) {
 107                 printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
 108                 return -ENOEXEC;
 109         }
 110
 111         if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
 112                 printk(KERN_ERR
 113                        "module %s: relocation overflow\n",
 114                        me->name);
 115                 return -ENOEXEC;
 116         }
 117
 118         *location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);
 119
 120         return 0;
 121 }
 122
 123 static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_Addr v)
 124 {
 125         struct mips_hi16 *n;
 126
 127         /*
 128          * We cannot relocate this one now because we don't know the value of
 129          * the carry we need to add.  Save the information, and let LO16 do the
 130          * actual relocation.
 131          */
 132         n = kmalloc(sizeof *n, GFP_KERNEL);
 133         if (!n)
 134                 return -ENOMEM;
 135
 136         n->addr = (Elf_Addr *)location;
 137         n->value = v;
 138         n->next = mips_hi16_list;
 139         mips_hi16_list = n;
 140
 141         return 0;
 142 }
 143
 144 static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)
 145 {
 146         *location = (*location & 0xffff0000) |
 147                     ((((long long) v + 0x8000LL) >> 16) & 0xffff);
 148
 149         return 0;
 150 }
 151
 152 static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)
 153 {
 154         unsigned long insnlo = *location;
 155         Elf_Addr val, vallo;
 156
 157         /* Sign extend the addend we extract from the lo insn.  */
 158         vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
 159
 160         if (mips_hi16_list != NULL) {
 161                 struct mips_hi16 *l;
 162
 163                 l = mips_hi16_list;
 164                 while (l != NULL) {
 165                         struct mips_hi16 *next;
 166                         unsigned long insn;
 167
 168                         /*
 169                          * The value for the HI16 had best be the same.
 170                          */
 171                         if (v != l->value)
 172                                 goto out_danger;
 173
 174                         /*
 175                          * Do the HI16 relocation.  Note that we actually don't
 176                          * need to know anything about the LO16 itself, except
 177                          * where to find the low 16 bits of the addend needed
 178                          * by the LO16.
 179                          */
 180                         insn = *l->addr;
 181                         val = ((insn & 0xffff) << 16) + vallo;
 182                         val += v;
 183
 184                         /*
 185                          * Account for the sign extension that will happen in
 186                          * the low bits.
 187                          */
 188                         val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;
 189
 190                         insn = (insn & ~0xffff) | val;
 191                         *l->addr = insn;
 192
 193                         next = l->next;
 194                         kfree(l);
 195                         l = next;
 196                 }
 197
 198                 mips_hi16_list = NULL;
 199         }
 200
 201         /*
 202          * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
 203          */
 204         val = v + vallo;
 205         insnlo = (insnlo & ~0xffff) | (val & 0xffff);
 206         *location = insnlo;
 207
 208         return 0;
 209
 210 out_danger:
 211         printk(KERN_ERR "module %s: dangerous " "relocation\n", me->name);
 212
 213         return -ENOEXEC;
 214 }
 215
 216 static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
 217 {
 218         *location = (*location & 0xffff0000) | (v & 0xffff);
 219
 220         return 0;
 221 }
 222
 223 static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
 224 {
 225         *(Elf_Addr *)location = v;
 226
 227         return 0;
 228 }
 229
 230 static int apply_r_mips_higher_rela(struct module *me, u32 *location,
 231                                     Elf_Addr v)
 232 {
 233         *location = (*location & 0xffff0000) |
 234                     ((((long long) v + 0x80008000LL) >> 32) & 0xffff);
 235
 236         return 0;
 237 }
 238
 239 static int apply_r_mips_highest_rela(struct module *me, u32 *location,
 240                                      Elf_Addr v)
 241 {
 242         *location = (*location & 0xffff0000) |
 243                     ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);
 244
 245         return 0;
 246 }
 247
 248 static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
 249                                 Elf_Addr v) = {
 250         [R_MIPS_NONE]           = apply_r_mips_none,
 251         [R_MIPS_32]             = apply_r_mips_32_rel,
 252         [R_MIPS_26]             = apply_r_mips_26_rel,
 253         [R_MIPS_HI16]           = apply_r_mips_hi16_rel,
 254         [R_MIPS_LO16]           = apply_r_mips_lo16_rel
 255 };
 256
 257 static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 258                                 Elf_Addr v) = {
 259         [R_MIPS_NONE]           = apply_r_mips_none,
 260         [R_MIPS_32]             = apply_r_mips_32_rela,
 261         [R_MIPS_26]             = apply_r_mips_26_rela,
 262         [R_MIPS_HI16]           = apply_r_mips_hi16_rela,
 263         [R_MIPS_LO16]           = apply_r_mips_lo16_rela,
 264         [R_MIPS_64]             = apply_r_mips_64_rela,
 265         [R_MIPS_HIGHER]         = apply_r_mips_higher_rela,
 266         [R_MIPS_HIGHEST]        = apply_r_mips_highest_rela
 267 };
 268
 269 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
 270                    unsigned int symindex, unsigned int relsec,
 271                    struct module *me)
 272 {
 273         Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr;
 274         Elf_Sym *sym;
 275         u32 *location;
 276         unsigned int i;
 277         Elf_Addr v;
 278         int res;
 279
 280         pr_debug("Applying relocate section %u to %u\n", relsec,
 281                sechdrs[relsec].sh_info);
 282
 283         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 284                 /* This is where to make the change */
 285                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 286                         + rel[i].r_offset;
 287                 /* This is the symbol it is referring to */
 288                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 289                         + ELF_MIPS_R_SYM(rel[i]);
 290                 if (!sym->st_value) {
 291                         /* Ignore unresolved weak symbol */
 292                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 293                                 continue;
 294                         printk(KERN_WARNING "%s: Unknown symbol %s\n",
 295                                me->name, strtab + sym->st_name);
 296                         return -ENOENT;
 297                 }
 298
 299                 v = sym->st_value;
 300
 301                 res = reloc_handlers_rel[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
 302                 if (res)
 303                         return res;
 304         }
 305
 306         return 0;
 307 }
 308
 309 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 310                        unsigned int symindex, unsigned int relsec,
 311                        struct module *me)
 312 {
 313         Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
 314         Elf_Sym *sym;
 315         u32 *location;
 316         unsigned int i;
 317         Elf_Addr v;
 318         int res;
 319
 320         pr_debug("Applying relocate section %u to %u\n", relsec,
 321                sechdrs[relsec].sh_info);
 322
 323         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 324                 /* This is where to make the change */
 325                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 326                         + rel[i].r_offset;
 327                 /* This is the symbol it is referring to */
 328                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 329                         + ELF_MIPS_R_SYM(rel[i]);
 330                 if (!sym->st_value) {
 331                         /* Ignore unresolved weak symbol */
 332                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 333                                 continue;
 334                         printk(KERN_WARNING "%s: Unknown symbol %s\n",
 335                                me->name, strtab + sym->st_name);
 336                         return -ENOENT;
 337                 }
 338
 339                 v = sym->st_value + rel[i].r_addend;
 340
 341                 res = reloc_handlers_rela[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
 342                 if (res)
 343                         return res;
 344         }
 345
 346         return 0;
 347 }
 348
 349 /* Given an address, look for it in the module exception tables. */
 350 const struct exception_table_entry *search_module_dbetables(unsigned long addr)
 351 {
 352         unsigned long flags;
 353         const struct exception_table_entry *e = NULL;
 354         struct mod_arch_specific *dbe;
 355
 356         spin_lock_irqsave(&dbe_lock, flags);
 357         list_for_each_entry(dbe, &dbe_list, dbe_list) {
 358                 e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr);
 359                 if (e)
 360                         break;
 361         }
 362         spin_unlock_irqrestore(&dbe_lock, flags);
 363
 364         /* Now, if we found one, we are running inside it now, hence
 365            we cannot unload the module, hence no refcnt needed. */
 366         return e;
 367 }
 368
 369 /* Put in dbe list if neccessary. */
 370 int module_finalize(const Elf_Ehdr *hdr,
 371                     const Elf_Shdr *sechdrs,
 372                     struct module *me)
 373 {
 374         const Elf_Shdr *s;
 375         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 376
 377         INIT_LIST_HEAD(&me->arch.dbe_list);
 378         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 379                 if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
 380                         continue;
 381                 me->arch.dbe_start = (void *)s->sh_addr;
 382                 me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
 383                 spin_lock_irq(&dbe_lock);
 384                 list_add(&me->arch.dbe_list, &dbe_list);
 385                 spin_unlock_irq(&dbe_lock);
 386         }
 387         return 0;
 388 }
 389
 390 void module_arch_cleanup(struct module *mod)
 391 {
 392         spin_lock_irq(&dbe_lock);
 393         list_del(&mod->arch.dbe_list);
 394         spin_unlock_irq(&dbe_lock);
 395 }