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 #include <asm/pgtable.h>        /* MODULE_START */
  33
  34 struct mips_hi16 {
  35         struct mips_hi16 *next;
  36         Elf_Addr *addr;
  37         Elf_Addr value;
  38 };
  39
  40 static struct mips_hi16 *mips_hi16_list;
  41
  42 static LIST_HEAD(dbe_list);
  43 static DEFINE_SPINLOCK(dbe_lock);
  44
  45 void *module_alloc(unsigned long size)
  46 {
  47 #ifdef MODULE_START
  48         struct vm_struct *area;
  49
  50         size = PAGE_ALIGN(size);
  51         if (!size)
  52                 return NULL;
  53
  54         area = __get_vm_area(size, VM_ALLOC, MODULE_START, MODULE_END);
  55         if (!area)
  56                 return NULL;
  57
  58         return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL);
  59 #else
  60         if (size == 0)
  61                 return NULL;
  62         return vmalloc(size);
  63 #endif
  64 }
  65
  66 /* Free memory returned from module_alloc */
  67 void module_free(struct module *mod, void *module_region)
  68 {
  69         vfree(module_region);
  70         /* FIXME: If module_region == mod->init_region, trim exception
  71            table entries. */
  72 }
  73
  74 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
  75                               char *secstrings, struct module *mod)
  76 {
  77         return 0;
  78 }
  79
  80 static int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v)
  81 {
  82         return 0;
  83 }
  84
  85 static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v)
  86 {
  87         *location += v;
  88
  89         return 0;
  90 }
  91
  92 static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
  93 {
  94         *location = v;
  95
  96         return 0;
  97 }
  98
  99 static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v)
 100 {
 101         if (v % 4) {
 102                 printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
 103                 return -ENOEXEC;
 104         }
 105
 106         if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
 107                 printk(KERN_ERR
 108                        "module %s: relocation overflow\n",
 109                        me->name);
 110                 return -ENOEXEC;
 111         }
 112
 113         *location = (*location & ~0x03ffffff) |
 114                     ((*location + (v >> 2)) & 0x03ffffff);
 115
 116         return 0;
 117 }
 118
 119 static int apply_r_mips_26_rela(struct module *me, u32 *location, Elf_Addr v)
 120 {
 121         if (v % 4) {
 122                 printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
 123                 return -ENOEXEC;
 124         }
 125
 126         if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
 127                 printk(KERN_ERR
 128                        "module %s: relocation overflow\n",
 129                        me->name);
 130                 return -ENOEXEC;
 131         }
 132
 133         *location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);
 134
 135         return 0;
 136 }
 137
 138 static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_Addr v)
 139 {
 140         struct mips_hi16 *n;
 141
 142         /*
 143          * We cannot relocate this one now because we don't know the value of
 144          * the carry we need to add.  Save the information, and let LO16 do the
 145          * actual relocation.
 146          */
 147         n = kmalloc(sizeof *n, GFP_KERNEL);
 148         if (!n)
 149                 return -ENOMEM;
 150
 151         n->addr = (Elf_Addr *)location;
 152         n->value = v;
 153         n->next = mips_hi16_list;
 154         mips_hi16_list = n;
 155
 156         return 0;
 157 }
 158
 159 static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)
 160 {
 161         *location = (*location & 0xffff0000) |
 162                     ((((long long) v + 0x8000LL) >> 16) & 0xffff);
 163
 164         return 0;
 165 }
 166
 167 static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)
 168 {
 169         unsigned long insnlo = *location;
 170         Elf_Addr val, vallo;
 171
 172         /* Sign extend the addend we extract from the lo insn.  */
 173         vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
 174
 175         if (mips_hi16_list != NULL) {
 176                 struct mips_hi16 *l;
 177
 178                 l = mips_hi16_list;
 179                 while (l != NULL) {
 180                         struct mips_hi16 *next;
 181                         unsigned long insn;
 182
 183                         /*
 184                          * The value for the HI16 had best be the same.
 185                          */
 186                         if (v != l->value)
 187                                 goto out_danger;
 188
 189                         /*
 190                          * Do the HI16 relocation.  Note that we actually don't
 191                          * need to know anything about the LO16 itself, except
 192                          * where to find the low 16 bits of the addend needed
 193                          * by the LO16.
 194                          */
 195                         insn = *l->addr;
 196                         val = ((insn & 0xffff) << 16) + vallo;
 197                         val += v;
 198
 199                         /*
 200                          * Account for the sign extension that will happen in
 201                          * the low bits.
 202                          */
 203                         val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;
 204
 205                         insn = (insn & ~0xffff) | val;
 206                         *l->addr = insn;
 207
 208                         next = l->next;
 209                         kfree(l);
 210                         l = next;
 211                 }
 212
 213                 mips_hi16_list = NULL;
 214         }
 215
 216         /*
 217          * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
 218          */
 219         val = v + vallo;
 220         insnlo = (insnlo & ~0xffff) | (val & 0xffff);
 221         *location = insnlo;
 222
 223         return 0;
 224
 225 out_danger:
 226         printk(KERN_ERR "module %s: dangerous " "relocation\n", me->name);
 227
 228         return -ENOEXEC;
 229 }
 230
 231 static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
 232 {
 233         *location = (*location & 0xffff0000) | (v & 0xffff);
 234
 235         return 0;
 236 }
 237
 238 static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
 239 {
 240         *(Elf_Addr *)location = v;
 241
 242         return 0;
 243 }
 244
 245 static int apply_r_mips_higher_rela(struct module *me, u32 *location,
 246                                     Elf_Addr v)
 247 {
 248         *location = (*location & 0xffff0000) |
 249                     ((((long long) v + 0x80008000LL) >> 32) & 0xffff);
 250
 251         return 0;
 252 }
 253
 254 static int apply_r_mips_highest_rela(struct module *me, u32 *location,
 255                                      Elf_Addr v)
 256 {
 257         *location = (*location & 0xffff0000) |
 258                     ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);
 259
 260         return 0;
 261 }
 262
 263 static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
 264                                 Elf_Addr v) = {
 265         [R_MIPS_NONE]           = apply_r_mips_none,
 266         [R_MIPS_32]             = apply_r_mips_32_rel,
 267         [R_MIPS_26]             = apply_r_mips_26_rel,
 268         [R_MIPS_HI16]           = apply_r_mips_hi16_rel,
 269         [R_MIPS_LO16]           = apply_r_mips_lo16_rel
 270 };
 271
 272 static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 273                                 Elf_Addr v) = {
 274         [R_MIPS_NONE]           = apply_r_mips_none,
 275         [R_MIPS_32]             = apply_r_mips_32_rela,
 276         [R_MIPS_26]             = apply_r_mips_26_rela,
 277         [R_MIPS_HI16]           = apply_r_mips_hi16_rela,
 278         [R_MIPS_LO16]           = apply_r_mips_lo16_rela,
 279         [R_MIPS_64]             = apply_r_mips_64_rela,
 280         [R_MIPS_HIGHER]         = apply_r_mips_higher_rela,
 281         [R_MIPS_HIGHEST]        = apply_r_mips_highest_rela
 282 };
 283
 284 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
 285                    unsigned int symindex, unsigned int relsec,
 286                    struct module *me)
 287 {
 288         Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr;
 289         Elf_Sym *sym;
 290         u32 *location;
 291         unsigned int i;
 292         Elf_Addr v;
 293         int res;
 294
 295         pr_debug("Applying relocate section %u to %u\n", relsec,
 296                sechdrs[relsec].sh_info);
 297
 298         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 299                 /* This is where to make the change */
 300                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 301                         + rel[i].r_offset;
 302                 /* This is the symbol it is referring to */
 303                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 304                         + ELF_MIPS_R_SYM(rel[i]);
 305                 if (!sym->st_value) {
 306                         /* Ignore unresolved weak symbol */
 307                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 308                                 continue;
 309                         printk(KERN_WARNING "%s: Unknown symbol %s\n",
 310                                me->name, strtab + sym->st_name);
 311                         return -ENOENT;
 312                 }
 313
 314                 v = sym->st_value;
 315
 316                 res = reloc_handlers_rel[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
 317                 if (res)
 318                         return res;
 319         }
 320
 321         return 0;
 322 }
 323
 324 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 325                        unsigned int symindex, unsigned int relsec,
 326                        struct module *me)
 327 {
 328         Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
 329         Elf_Sym *sym;
 330         u32 *location;
 331         unsigned int i;
 332         Elf_Addr v;
 333         int res;
 334
 335         pr_debug("Applying relocate section %u to %u\n", relsec,
 336                sechdrs[relsec].sh_info);
 337
 338         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 339                 /* This is where to make the change */
 340                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 341                         + rel[i].r_offset;
 342                 /* This is the symbol it is referring to */
 343                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 344                         + ELF_MIPS_R_SYM(rel[i]);
 345                 if (!sym->st_value) {
 346                         /* Ignore unresolved weak symbol */
 347                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 348                                 continue;
 349                         printk(KERN_WARNING "%s: Unknown symbol %s\n",
 350                                me->name, strtab + sym->st_name);
 351                         return -ENOENT;
 352                 }
 353
 354                 v = sym->st_value + rel[i].r_addend;
 355
 356                 res = reloc_handlers_rela[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
 357                 if (res)
 358                         return res;
 359         }
 360
 361         return 0;
 362 }
 363
 364 /* Given an address, look for it in the module exception tables. */
 365 const struct exception_table_entry *search_module_dbetables(unsigned long addr)
 366 {
 367         unsigned long flags;
 368         const struct exception_table_entry *e = NULL;
 369         struct mod_arch_specific *dbe;
 370
 371         spin_lock_irqsave(&dbe_lock, flags);
 372         list_for_each_entry(dbe, &dbe_list, dbe_list) {
 373                 e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr);
 374                 if (e)
 375                         break;
 376         }
 377         spin_unlock_irqrestore(&dbe_lock, flags);
 378
 379         /* Now, if we found one, we are running inside it now, hence
 380            we cannot unload the module, hence no refcnt needed. */
 381         return e;
 382 }
 383
 384 /* Put in dbe list if necessary. */
 385 int module_finalize(const Elf_Ehdr *hdr,
 386                     const Elf_Shdr *sechdrs,
 387                     struct module *me)
 388 {
 389         const Elf_Shdr *s;
 390         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 391
 392         INIT_LIST_HEAD(&me->arch.dbe_list);
 393         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 394                 if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
 395                         continue;
 396                 me->arch.dbe_start = (void *)s->sh_addr;
 397                 me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
 398                 spin_lock_irq(&dbe_lock);
 399                 list_add(&me->arch.dbe_list, &dbe_list);
 400                 spin_unlock_irq(&dbe_lock);
 401         }
 402         return 0;
 403 }
 404
 405 void module_arch_cleanup(struct module *mod)
 406 {
 407         spin_lock_irq(&dbe_lock);
 408         list_del(&mod->arch.dbe_list);
 409         spin_unlock_irq(&dbe_lock);
 410 }