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 LIST_HEAD(dbe_list);
  43 static DEFINE_SPINLOCK(dbe_lock);
  44
  45 #ifdef MODULE_START
  46 void *module_alloc(unsigned long size)
  47 {
  48         return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END,
  49                                 GFP_KERNEL, PAGE_KERNEL, -1,
  50                                 __builtin_return_address(0));
  51 }
  52 #endif
  53
  54 int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v)
  55 {
  56         return 0;
  57 }
  58
  59 static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v)
  60 {
  61         *location += v;
  62
  63         return 0;
  64 }
  65
  66 static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v)
  67 {
  68         if (v % 4) {
  69                 pr_err("module %s: dangerous R_MIPS_26 REL relocation\n",
  70                        me->name);
  71                 return -ENOEXEC;
  72         }
  73
  74         if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
  75                 printk(KERN_ERR
  76                        "module %s: relocation overflow\n",
  77                        me->name);
  78                 return -ENOEXEC;
  79         }
  80
  81         *location = (*location & ~0x03ffffff) |
  82                     ((*location + (v >> 2)) & 0x03ffffff);
  83
  84         return 0;
  85 }
  86
  87 static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_Addr v)
  88 {
  89         struct mips_hi16 *n;
  90
  91         /*
  92          * We cannot relocate this one now because we don't know the value of
  93          * the carry we need to add.  Save the information, and let LO16 do the
  94          * actual relocation.
  95          */
  96         n = kmalloc(sizeof *n, GFP_KERNEL);
  97         if (!n)
  98                 return -ENOMEM;
  99
 100         n->addr = (Elf_Addr *)location;
 101         n->value = v;
 102         n->next = me->arch.r_mips_hi16_list;
 103         me->arch.r_mips_hi16_list = n;
 104
 105         return 0;
 106 }
 107
 108 static void free_relocation_chain(struct mips_hi16 *l)
 109 {
 110         struct mips_hi16 *next;
 111
 112         while (l) {
 113                 next = l->next;
 114                 kfree(l);
 115                 l = next;
 116         }
 117 }
 118
 119 static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)
 120 {
 121         unsigned long insnlo = *location;
 122         struct mips_hi16 *l;
 123         Elf_Addr val, vallo;
 124
 125         /* Sign extend the addend we extract from the lo insn.  */
 126         vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
 127
 128         if (me->arch.r_mips_hi16_list != NULL) {
 129                 l = me->arch.r_mips_hi16_list;
 130                 while (l != NULL) {
 131                         struct mips_hi16 *next;
 132                         unsigned long insn;
 133
 134                         /*
 135                          * The value for the HI16 had best be the same.
 136                          */
 137                         if (v != l->value)
 138                                 goto out_danger;
 139
 140                         /*
 141                          * Do the HI16 relocation.  Note that we actually don't
 142                          * need to know anything about the LO16 itself, except
 143                          * where to find the low 16 bits of the addend needed
 144                          * by the LO16.
 145                          */
 146                         insn = *l->addr;
 147                         val = ((insn & 0xffff) << 16) + vallo;
 148                         val += v;
 149
 150                         /*
 151                          * Account for the sign extension that will happen in
 152                          * the low bits.
 153                          */
 154                         val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;
 155
 156                         insn = (insn & ~0xffff) | val;
 157                         *l->addr = insn;
 158
 159                         next = l->next;
 160                         kfree(l);
 161                         l = next;
 162                 }
 163
 164                 me->arch.r_mips_hi16_list = NULL;
 165         }
 166
 167         /*
 168          * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
 169          */
 170         val = v + vallo;
 171         insnlo = (insnlo & ~0xffff) | (val & 0xffff);
 172         *location = insnlo;
 173
 174         return 0;
 175
 176 out_danger:
 177         free_relocation_chain(l);
 178         me->arch.r_mips_hi16_list = NULL;
 179
 180         pr_err("module %s: dangerous R_MIPS_LO16 REL relocation\n", me->name);
 181
 182         return -ENOEXEC;
 183 }
 184
 185 static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
 186                                 Elf_Addr v) = {
 187         [R_MIPS_NONE]           = apply_r_mips_none,
 188         [R_MIPS_32]             = apply_r_mips_32_rel,
 189         [R_MIPS_26]             = apply_r_mips_26_rel,
 190         [R_MIPS_HI16]           = apply_r_mips_hi16_rel,
 191         [R_MIPS_LO16]           = apply_r_mips_lo16_rel
 192 };
 193
 194 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
 195                    unsigned int symindex, unsigned int relsec,
 196                    struct module *me)
 197 {
 198         Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr;
 199         Elf_Sym *sym;
 200         u32 *location;
 201         unsigned int i;
 202         Elf_Addr v;
 203         int res;
 204
 205         pr_debug("Applying relocate section %u to %u\n", relsec,
 206                sechdrs[relsec].sh_info);
 207
 208         me->arch.r_mips_hi16_list = NULL;
 209         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 210                 /* This is where to make the change */
 211                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 212                         + rel[i].r_offset;
 213                 /* This is the symbol it is referring to */
 214                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 215                         + ELF_MIPS_R_SYM(rel[i]);
 216                 if (IS_ERR_VALUE(sym->st_value)) {
 217                         /* Ignore unresolved weak symbol */
 218                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 219                                 continue;
 220                         printk(KERN_WARNING "%s: Unknown symbol %s\n",
 221                                me->name, strtab + sym->st_name);
 222                         return -ENOENT;
 223                 }
 224
 225                 v = sym->st_value;
 226
 227                 res = reloc_handlers_rel[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
 228                 if (res)
 229                         return res;
 230         }
 231
 232         /*
 233          * Normally the hi16 list should be deallocated at this point.  A
 234          * malformed binary however could contain a series of R_MIPS_HI16
 235          * relocations not followed by a R_MIPS_LO16 relocation.  In that
 236          * case, free up the list and return an error.
 237          */
 238         if (me->arch.r_mips_hi16_list) {
 239                 free_relocation_chain(me->arch.r_mips_hi16_list);
 240                 me->arch.r_mips_hi16_list = NULL;
 241
 242                 return -ENOEXEC;
 243         }
 244
 245         return 0;
 246 }
 247
 248 /* Given an address, look for it in the module exception tables. */
 249 const struct exception_table_entry *search_module_dbetables(unsigned long addr)
 250 {
 251         unsigned long flags;
 252         const struct exception_table_entry *e = NULL;
 253         struct mod_arch_specific *dbe;
 254
 255         spin_lock_irqsave(&dbe_lock, flags);
 256         list_for_each_entry(dbe, &dbe_list, dbe_list) {
 257                 e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr);
 258                 if (e)
 259                         break;
 260         }
 261         spin_unlock_irqrestore(&dbe_lock, flags);
 262
 263         /* Now, if we found one, we are running inside it now, hence
 264            we cannot unload the module, hence no refcnt needed. */
 265         return e;
 266 }
 267
 268 /* Put in dbe list if necessary. */
 269 int module_finalize(const Elf_Ehdr *hdr,
 270                     const Elf_Shdr *sechdrs,
 271                     struct module *me)
 272 {
 273         const Elf_Shdr *s;
 274         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 275
 276         /* Make jump label nops. */
 277         jump_label_apply_nops(me);
 278
 279         INIT_LIST_HEAD(&me->arch.dbe_list);
 280         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 281                 if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
 282                         continue;
 283                 me->arch.dbe_start = (void *)s->sh_addr;
 284                 me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
 285                 spin_lock_irq(&dbe_lock);
 286                 list_add(&me->arch.dbe_list, &dbe_list);
 287                 spin_unlock_irq(&dbe_lock);
 288         }
 289         return 0;
 290 }
 291
 292 void module_arch_cleanup(struct module *mod)
 293 {
 294         spin_lock_irq(&dbe_lock);
 295         list_del(&mod->arch.dbe_list);
 296         spin_unlock_irq(&dbe_lock);
 297 }