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