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