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