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/numa.h>
  27 #include <linux/vmalloc.h>
  28 #include <linux/slab.h>
  29 #include <linux/fs.h>
  30 #include <linux/string.h>
  31 #include <linux/kernel.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 LIST_HEAD(dbe_list);
  44 static DEFINE_SPINLOCK(dbe_lock);
  45
  46 #ifdef MODULE_START
  47 void *module_alloc(unsigned long size)
  48 {
  49         return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END,
  50                                 GFP_KERNEL, PAGE_KERNEL, NUMA_NO_NODE,
  51                                 __builtin_return_address(0));
  52 }
  53 #endif
  54
  55 int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v)
  56 {
  57         return 0;
  58 }
  59
  60 static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v)
  61 {
  62         *location += v;
  63
  64         return 0;
  65 }
  66
  67 static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v)
  68 {
  69         if (v % 4) {
  70                 pr_err("module %s: dangerous R_MIPS_26 REL relocation\n",
  71                        me->name);
  72                 return -ENOEXEC;
  73         }
  74
  75         if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
  76                 printk(KERN_ERR
  77                        "module %s: relocation overflow\n",
  78                        me->name);
  79                 return -ENOEXEC;
  80         }
  81
  82         *location = (*location & ~0x03ffffff) |
  83                     ((*location + (v >> 2)) & 0x03ffffff);
  84
  85         return 0;
  86 }
  87
  88 static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_Addr v)
  89 {
  90         struct mips_hi16 *n;
  91
  92         /*
  93          * We cannot relocate this one now because we don't know the value of
  94          * the carry we need to add.  Save the information, and let LO16 do the
  95          * actual relocation.
  96          */
  97         n = kmalloc(sizeof *n, GFP_KERNEL);
  98         if (!n)
  99                 return -ENOMEM;
 100
 101         n->addr = (Elf_Addr *)location;
 102         n->value = v;
 103         n->next = me->arch.r_mips_hi16_list;
 104         me->arch.r_mips_hi16_list = n;
 105
 106         return 0;
 107 }
 108
 109 static void free_relocation_chain(struct mips_hi16 *l)
 110 {
 111         struct mips_hi16 *next;
 112
 113         while (l) {
 114                 next = l->next;
 115                 kfree(l);
 116                 l = next;
 117         }
 118 }
 119
 120 static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)
 121 {
 122         unsigned long insnlo = *location;
 123         struct mips_hi16 *l;
 124         Elf_Addr val, vallo;
 125
 126         /* Sign extend the addend we extract from the lo insn.  */
 127         vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
 128
 129         if (me->arch.r_mips_hi16_list != NULL) {
 130                 l = me->arch.r_mips_hi16_list;
 131                 while (l != NULL) {
 132                         struct mips_hi16 *next;
 133                         unsigned long insn;
 134
 135                         /*
 136                          * The value for the HI16 had best be the same.
 137                          */
 138                         if (v != l->value)
 139                                 goto out_danger;
 140
 141                         /*
 142                          * Do the HI16 relocation.  Note that we actually don't
 143                          * need to know anything about the LO16 itself, except
 144                          * where to find the low 16 bits of the addend needed
 145                          * by the LO16.
 146                          */
 147                         insn = *l->addr;
 148                         val = ((insn & 0xffff) << 16) + vallo;
 149                         val += v;
 150
 151                         /*
 152                          * Account for the sign extension that will happen in
 153                          * the low bits.
 154                          */
 155                         val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;
 156
 157                         insn = (insn & ~0xffff) | val;
 158                         *l->addr = insn;
 159
 160                         next = l->next;
 161                         kfree(l);
 162                         l = next;
 163                 }
 164
 165                 me->arch.r_mips_hi16_list = NULL;
 166         }
 167
 168         /*
 169          * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
 170          */
 171         val = v + vallo;
 172         insnlo = (insnlo & ~0xffff) | (val & 0xffff);
 173         *location = insnlo;
 174
 175         return 0;
 176
 177 out_danger:
 178         free_relocation_chain(l);
 179         me->arch.r_mips_hi16_list = NULL;
 180
 181         pr_err("module %s: dangerous R_MIPS_LO16 REL relocation\n", me->name);
 182
 183         return -ENOEXEC;
 184 }
 185
 186 static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
 187                                 Elf_Addr v) = {
 188         [R_MIPS_NONE]           = apply_r_mips_none,
 189         [R_MIPS_32]             = apply_r_mips_32_rel,
 190         [R_MIPS_26]             = apply_r_mips_26_rel,
 191         [R_MIPS_HI16]           = apply_r_mips_hi16_rel,
 192         [R_MIPS_LO16]           = apply_r_mips_lo16_rel
 193 };
 194
 195 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
 196                    unsigned int symindex, unsigned int relsec,
 197                    struct module *me)
 198 {
 199         Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr;
 200         Elf_Sym *sym;
 201         u32 *location;
 202         unsigned int i;
 203         Elf_Addr v;
 204         int res;
 205
 206         pr_debug("Applying relocate section %u to %u\n", relsec,
 207                sechdrs[relsec].sh_info);
 208
 209         me->arch.r_mips_hi16_list = NULL;
 210         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 211                 /* This is where to make the change */
 212                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 213                         + rel[i].r_offset;
 214                 /* This is the symbol it is referring to */
 215                 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 216                         + ELF_MIPS_R_SYM(rel[i]);
 217                 if (IS_ERR_VALUE(sym->st_value)) {
 218                         /* Ignore unresolved weak symbol */
 219                         if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
 220                                 continue;
 221                         printk(KERN_WARNING "%s: Unknown symbol %s\n",
 222                                me->name, strtab + sym->st_name);
 223                         return -ENOENT;
 224                 }
 225
 226                 v = sym->st_value;
 227
 228                 res = reloc_handlers_rel[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
 229                 if (res)
 230                         return res;
 231         }
 232
 233         /*
 234          * Normally the hi16 list should be deallocated at this point.  A
 235          * malformed binary however could contain a series of R_MIPS_HI16
 236          * relocations not followed by a R_MIPS_LO16 relocation.  In that
 237          * case, free up the list and return an error.
 238          */
 239         if (me->arch.r_mips_hi16_list) {
 240                 free_relocation_chain(me->arch.r_mips_hi16_list);
 241                 me->arch.r_mips_hi16_list = NULL;
 242
 243                 return -ENOEXEC;
 244         }
 245
 246         return 0;
 247 }
 248
 249 /* Given an address, look for it in the module exception tables. */
 250 const struct exception_table_entry *search_module_dbetables(unsigned long addr)
 251 {
 252         unsigned long flags;
 253         const struct exception_table_entry *e = NULL;
 254         struct mod_arch_specific *dbe;
 255
 256         spin_lock_irqsave(&dbe_lock, flags);
 257         list_for_each_entry(dbe, &dbe_list, dbe_list) {
 258                 e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr);
 259                 if (e)
 260                         break;
 261         }
 262         spin_unlock_irqrestore(&dbe_lock, flags);
 263
 264         /* Now, if we found one, we are running inside it now, hence
 265            we cannot unload the module, hence no refcnt needed. */
 266         return e;
 267 }
 268
 269 /* Put in dbe list if necessary. */
 270 int module_finalize(const Elf_Ehdr *hdr,
 271                     const Elf_Shdr *sechdrs,
 272                     struct module *me)
 273 {
 274         const Elf_Shdr *s;
 275         char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 276
 277         /* Make jump label nops. */
 278         jump_label_apply_nops(me);
 279
 280         INIT_LIST_HEAD(&me->arch.dbe_list);
 281         for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
 282                 if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
 283                         continue;
 284                 me->arch.dbe_start = (void *)s->sh_addr;
 285                 me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
 286                 spin_lock_irq(&dbe_lock);
 287                 list_add(&me->arch.dbe_list, &dbe_list);
 288                 spin_unlock_irq(&dbe_lock);
 289         }
 290         return 0;
 291 }
 292
 293 void module_arch_cleanup(struct module *mod)
 294 {
 295         spin_lock_irq(&dbe_lock);
 296         list_del(&mod->arch.dbe_list);
 297         spin_unlock_irq(&dbe_lock);
 298 }