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 <asm/pgtable.h>        /* MODULE_START */
  34
  35 struct mips_hi16 {
  36         struct mips_hi16 *next;
  37         Elf_Addr *addr;
  38         Elf_Addr value;
  39 };
  40
  41 static struct mips_hi16 *mips_hi16_list;
  42
  43 static LIST_HEAD(dbe_list);
  44 static DEFINE_SPINLOCK(dbe_lock);
  45
  46 void *module_alloc(unsigned long size)
  47 {
  48 #ifdef MODULE_START
  49         struct vm_struct *area;
  50
  51         size = PAGE_ALIGN(size);
  52         if (!size)
  53                 return NULL;
  54
  55         area = __get_vm_area(size, VM_ALLOC, MODULE_START, MODULE_END);
  56         if (!area)
  57                 return NULL;
  58
  59         return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL);
  60 #else
  61         if (size == 0)
  62                 return NULL;
  63         return vmalloc(size);
  64 #endif
  65 }
  66
  67 /* Free memory returned from module_alloc */
  68 void module_free(struct module *mod, void *module_region)
  69 {
  70         vfree(module_region);
  71 }
  72
  73 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
  74                               char *secstrings, struct module *mod)
  75 {
  76         return 0;
  77 }
  78
  79 static int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v)
  80 {
  81         return 0;
  82 }
  83
  84 static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v)
  85 {
  86         *location += v;
  87
  88         return 0;
  89 }
  90
  91 static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
  92 {
  93         *location = v;
  94
  95         return 0;
  96 }
  97
  98 static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v)
  99 {
 100         if (v % 4) {
 101                 pr_err("module %s: dangerous R_MIPS_26 REL relocation\n",
 102                        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                 pr_err("module %s: dangerous R_MIPS_26 RELArelocation\n",
 123                        me->name);
 124                 return -ENOEXEC;
 125         }
 126
 127         if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
 128                 printk(KERN_ERR
 129                        "module %s: relocation overflow\n",
 130                        me->name);
 131                 return -ENOEXEC;
 132         }
 133
 134         *location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);
 135
 136         return 0;
 137 }
 138
 139 static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_Addr v)
 140 {
 141         struct mips_hi16 *n;
 142
 143         /*
 144          * We cannot relocate this one now because we don't know the value of
 145          * the carry we need to add.  Save the information, and let LO16 do the
 146          * actual relocation.
 147          */
 148         n = kmalloc(sizeof *n, GFP_KERNEL);
 149         if (!n)
 150                 return -ENOMEM;
 151
 152         n->addr = (Elf_Addr *)location;
 153         n->value = v;
 154         n->next = mips_hi16_list;
 155         mips_hi16_list = n;
 156
 157         return 0;
 158 }
 159
 160 static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)
 161 {
 162         *location = (*location & 0xffff0000) |
 163                     ((((long long) v + 0x8000LL) >> 16) & 0xffff);
 164
 165         return 0;
 166 }
 167
 168 static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)
 169 {
 170         unsigned long insnlo = *location;
 171         Elf_Addr val, vallo;
 172
 173         /* Sign extend the addend we extract from the lo insn.  */
 174         vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
 175
 176         if (mips_hi16_list != NULL) {
 177                 struct mips_hi16 *l;
 178
 179                 l = mips_hi16_list;
 180                 while (l != NULL) {
 181                         struct mips_hi16 *next;
 182                         unsigned long insn;
 183
 184                         /*
 185                          * The value for the HI16 had best be the same.
 186                          */
 187                         if (v != l->value)
 188                                 goto out_danger;
 189
 190                         /*
 191                          * Do the HI16 relocation.  Note that we actually don't
 192                          * need to know anything about the LO16 itself, except
 193                          * where to find the low 16 bits of the addend needed
 194                          * by the LO16.
 195                          */
 196                         insn = *l->addr;
 197                         val = ((insn & 0xffff) << 16) + vallo;
 198                         val += v;
 199
 200                         /*
 201                          * Account for the sign extension that will happen in
 202                          * the low bits.
 203                          */
 204                         val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;
 205
 206                         insn = (insn & ~0xffff) | val;
 207                         *l->addr = insn;
 208
 209                         next = l->next;
 210                         kfree(l);
 211                         l = next;
 212                 }
 213
 214                 mips_hi16_list = NULL;
 215         }
 216
 217         /*
 218          * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
 219          */
 220         val = v + vallo;
 221         insnlo = (insnlo & ~0xffff) | (val & 0xffff);
 222         *location = insnlo;
 223
 224         return 0;
 225
 226 out_danger:
 227         pr_err("module %s: dangerous R_MIPS_LO16 REL relocation\n", me->name);
 228
 229         return -ENOEXEC;
 230 }
 231
 232 static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
 233 {
 234         *location = (*location & 0xffff0000) | (v & 0xffff);
 235
 236         return 0;
 237 }
 238
 239 static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
 240 {
 241         *(Elf_Addr *)location = v;
 242
 243         return 0;
 244 }
 245
 246 static int apply_r_mips_higher_rela(struct module *me, u32 *location,
 247                                     Elf_Addr v)
 248 {
 249         *location = (*location & 0xffff0000) |
 250                     ((((long long) v + 0x80008000LL) >> 32) & 0xffff);
 251
 252         return 0;
 253 }
 254
 255 static int apply_r_mips_highest_rela(struct module *me, u32 *location,
 256                                      Elf_Addr v)
 257 {
 258         *location = (*location & 0xffff0000) |
 259                     ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);
 260
 261         return 0;
 262 }
 263
 264 static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
 265                                 Elf_Addr v) = {
 266         [R_MIPS_NONE]           = apply_r_mips_none,
 267         [R_MIPS_32]             = apply_r_mips_32_rel,
 268         [R_MIPS_26]             = apply_r_mips_26_rel,
 269         [R_MIPS_HI16]           = apply_r_mips_hi16_rel,
 270         [R_MIPS_LO16]           = apply_r_mips_lo16_rel
 271 };
 272
 273 static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 274                                 Elf_Addr v) = {
 275         [R_MIPS_NONE]           = apply_r_mips_none,
 276         [R_MIPS_32]             = apply_r_mips_32_rela,
 277         [R_MIPS_26]             = apply_r_mips_26_rela,
 278         [R_MIPS_HI16]           = apply_r_mips_hi16_rela,
 279         [R_MIPS_LO16]           = apply_r_mips_lo16_rela,
 280         [R_MIPS_64]             = apply_r_mips_64_rela,
 281         [R_MIPS_HIGHER]         = apply_r_mips_higher_rela,
 282         [R_MIPS_HIGHEST]        = apply_r_mips_highest_rela
 283 };
 284
 285 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
 286                    unsigned int symindex, unsigned int relsec,
 287                    struct module *me)
 288 {
 289         Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr;
 290         Elf_Sym *sym;
 291         u32 *location;
 292         unsigned int i;
 293         Elf_Addr v;
 294         int res;
 295
 296         pr_debug("Applying relocate section %u to %u\n", relsec,
 297                sechdrs[relsec].sh_info);
 298
 299         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 300                 /* This is where to make the change */
 301                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 302                         + rel[i].r_offset;
 303                 /* This is the symbol it is referring to */
 304                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 305                         + ELF_MIPS_R_SYM(rel[i]);
 306                 if (IS_ERR_VALUE(sym->st_value)) {
 307                         /* Ignore unresolved weak symbol */
 308                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 309                                 continue;
 310                         printk(KERN_WARNING "%s: Unknown symbol %s\n",
 311                                me->name, strtab + sym->st_name);
 312                         return -ENOENT;
 313                 }
 314
 315                 v = sym->st_value;
 316
 317                 res = reloc_handlers_rel[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
 318                 if (res)
 319                         return res;
 320         }
 321
 322         return 0;
 323 }
 324
 325 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 326                        unsigned int symindex, unsigned int relsec,
 327                        struct module *me)
 328 {
 329         Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
 330         Elf_Sym *sym;
 331         u32 *location;
 332         unsigned int i;
 333         Elf_Addr v;
 334         int res;
 335
 336         pr_debug("Applying relocate section %u to %u\n", relsec,
 337                sechdrs[relsec].sh_info);
 338
 339         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 340                 /* This is where to make the change */
 341                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 342                         + rel[i].r_offset;
 343                 /* This is the symbol it is referring to */
 344                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 345                         + ELF_MIPS_R_SYM(rel[i]);
 346                 if (IS_ERR_VALUE(sym->st_value)) {
 347                         /* Ignore unresolved weak symbol */
 348                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 349                                 continue;
 350                         printk(KERN_WARNING "%s: Unknown symbol %s\n",
 351                                me->name, strtab + sym->st_name);
 352                         return -ENOENT;
 353                 }
 354
 355                 v = sym->st_value + rel[i].r_addend;
 356
 357                 res = reloc_handlers_rela[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
 358                 if (res)
 359                         return res;
 360         }
 361
 362         return 0;
 363 }
 364
 365 /* Given an address, look for it in the module exception tables. */
 366 const struct exception_table_entry *search_module_dbetables(unsigned long addr)
 367 {
 368         unsigned long flags;
 369         const struct exception_table_entry *e = NULL;
 370         struct mod_arch_specific *dbe;
 371
 372         spin_lock_irqsave(&dbe_lock, flags);
 373         list_for_each_entry(dbe, &dbe_list, dbe_list) {
 374                 e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr);
 375                 if (e)
 376                         break;
 377         }
 378         spin_unlock_irqrestore(&dbe_lock, flags);
 379
 380         /* Now, if we found one, we are running inside it now, hence
 381            we cannot unload the module, hence no refcnt needed. */
 382         return e;
 383 }
 384
 385 /* Put in dbe list if necessary. */
 386 int module_finalize(const Elf_Ehdr *hdr,
 387                     const Elf_Shdr *sechdrs,
 388                     struct module *me)
 389 {
 390         const Elf_Shdr *s;
 391         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 392
 393         INIT_LIST_HEAD(&me->arch.dbe_list);
 394         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 395                 if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
 396                         continue;
 397                 me->arch.dbe_start = (void *)s->sh_addr;
 398                 me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
 399                 spin_lock_irq(&dbe_lock);
 400                 list_add(&me->arch.dbe_list, &dbe_list);
 401                 spin_unlock_irq(&dbe_lock);
 402         }
 403         return 0;
 404 }
 405
 406 void module_arch_cleanup(struct module *mod)
 407 {
 408         spin_lock_irq(&dbe_lock);
 409         list_del(&mod->arch.dbe_list);
 410         spin_unlock_irq(&dbe_lock);
 411 }