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