LXR linux/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
  36struct mips_hi16 {
  37        struct mips_hi16 *next;
  38        Elf_Addr *addr;
  39        Elf_Addr value;
  40};
  41
  42static struct mips_hi16 *mips_hi16_list;
  43
  44static LIST_HEAD(dbe_list);
  45static DEFINE_SPINLOCK(dbe_lock);
  46
  47#ifdef MODULE_START
  48void *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
  56static int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v)
  57{
  58        return 0;
  59}
  60
  61static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v)
  62{
  63        *location += v;
  64
  65        return 0;
  66}
  67
  68static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
  69{
  70        *location = v;
  71
  72        return 0;
  73}
  74
  75static 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
  96static 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
 116static 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
 137static 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
 145static 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
 203out_danger:
 204        pr_err("module %s: dangerous R_MIPS_LO16 REL relocation\n", me->name);
 205
 206        return -ENOEXEC;
 207}
 208
 209static 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
 216static 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
 223static 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
 232static 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
 241static 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
 250static 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
 262int 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
 302int 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. */
 343const 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. */
 363int 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
 386void 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}
 392