arch/mips/kernel/module-elf64.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  */
  19
  20 #undef DEBUG
  21
  22 #include <linux/moduleloader.h>
  23 #include <linux/elf.h>
  24 #include <linux/vmalloc.h>
  25 #include <linux/slab.h>
  26 #include <linux/fs.h>
  27 #include <linux/string.h>
  28 #include <linux/kernel.h>
  29
  30 struct mips_hi16 {
  31         struct mips_hi16 *next;
  32         Elf32_Addr *addr;
  33         Elf64_Addr value;
  34 };
  35
  36 static struct mips_hi16 *mips_hi16_list;
  37
  38 void *module_alloc(unsigned long size)
  39 {
  40         if (size == 0)
  41                 return NULL;
  42         return vmalloc(size);
  43 }
  44
  45
  46 /* Free memory returned from module_alloc */
  47 void module_free(struct module *mod, void *module_region)
  48 {
  49         vfree(module_region);
  50         /* FIXME: If module_region == mod->init_region, trim exception
  51            table entries. */
  52 }
  53
  54 int module_frob_arch_sections(Elf_Ehdr *hdr,
  55                               Elf_Shdr *sechdrs,
  56                               char *secstrings,
  57                               struct module *mod)
  58 {
  59         return 0;
  60 }
  61
  62 int apply_relocate(Elf64_Shdr *sechdrs,
  63                    const char *strtab,
  64                    unsigned int symindex,
  65                    unsigned int relsec,
  66                    struct module *me)
  67 {
  68         /*
  69          * We don't want to deal with REL relocations - RELA is so much saner.
  70          */
  71         if (!sechdrs[relsec].sh_size)
  72                 return 0;
  73
  74         printk(KERN_ERR "module %s: REL relocation unsupported\n",
  75                me->name);
  76         return -ENOEXEC;
  77 }
  78
  79 static int apply_r_mips_none(struct module *me, uint32_t *location,
  80         Elf64_Addr v)
  81 {
  82         return 0;
  83 }
  84
  85 static int apply_r_mips_32(struct module *me, uint32_t *location,
  86         Elf64_Addr v)
  87 {
  88         *location = v;
  89
  90         return 0;
  91 }
  92
  93 static int apply_r_mips_26(struct module *me, uint32_t *location,
  94         Elf64_Addr v)
  95 {
  96         if (v % 4) {
  97                 printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
  98                 return -ENOEXEC;
  99         }
 100
 101         if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
 102                 printk(KERN_ERR
 103                        "module %s: relocation overflow\n",
 104                        me->name);
 105                 return -ENOEXEC;
 106         }
 107
 108         *location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);
 109
 110         return 0;
 111 }
 112
 113 static int apply_r_mips_hi16(struct module *me, uint32_t *location,
 114         Elf64_Addr v)
 115 {
 116         struct mips_hi16 *n;
 117
 118         /*
 119          * We cannot relocate this one now because we don't know the value of
 120          * the carry we need to add.  Save the information, and let LO16 do the
 121          * actual relocation.
 122          */
 123         n = kmalloc(sizeof *n, GFP_KERNEL);
 124         if (!n)
 125                 return -ENOMEM;
 126
 127         n->addr = location;
 128         n->value = v;
 129         n->next = mips_hi16_list;
 130         mips_hi16_list = n;
 131
 132         return 0;
 133 }
 134
 135 static int apply_r_mips_lo16(struct module *me, uint32_t *location,
 136         Elf64_Addr v)
 137 {
 138         unsigned long insnlo = *location;
 139         Elf32_Addr val, vallo;
 140
 141         /* Sign extend the addend we extract from the lo insn.  */
 142         vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;
 143
 144         if (mips_hi16_list != NULL) {
 145                 struct mips_hi16 *l;
 146
 147                 l = mips_hi16_list;
 148                 while (l != NULL) {
 149                         struct mips_hi16 *next;
 150                         unsigned long insn;
 151
 152                         /*
 153                          * The value for the HI16 had best be the same.
 154                          */
 155                         if (v != l->value)
 156                                 goto out_danger;
 157
 158                         /*
 159                          * Do the HI16 relocation.  Note that we actually don't
 160                          * need to know anything about the LO16 itself, except
 161                          * where to find the low 16 bits of the addend needed
 162                          * by the LO16.
 163                          */
 164                         insn = *l->addr;
 165                         val = ((insn & 0xffff) << 16) + vallo;
 166                         val += v;
 167
 168                         /*
 169                          * Account for the sign extension that will happen in
 170                          * the low bits.
 171                          */
 172                         val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;
 173
 174                         insn = (insn & ~0xffff) | val;
 175                         *l->addr = insn;
 176
 177                         next = l->next;
 178                         kfree(l);
 179                         l = next;
 180                 }
 181
 182                 mips_hi16_list = NULL;
 183         }
 184
 185         /*
 186          * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
 187          */
 188         insnlo = (insnlo & ~0xffff) | (v & 0xffff);
 189         *location = insnlo;
 190
 191         return 0;
 192
 193 out_danger:
 194         printk(KERN_ERR "module %s: dangerous " "relocation\n", me->name);
 195
 196         return -ENOEXEC;
 197 }
 198
 199 static int apply_r_mips_64(struct module *me, uint32_t *location,
 200         Elf64_Addr v)
 201 {
 202         *(uint64_t *) location = v;
 203
 204         return 0;
 205 }
 206
 207
 208 static int apply_r_mips_higher(struct module *me, uint32_t *location,
 209         Elf64_Addr v)
 210 {
 211         *location = (*location & 0xffff0000) |
 212                     ((((long long) v + 0x80008000LL) >> 32) & 0xffff);
 213
 214         return 0;
 215 }
 216
 217 static int apply_r_mips_highest(struct module *me, uint32_t *location,
 218         Elf64_Addr v)
 219 {
 220         *location = (*location & 0xffff0000) |
 221                     ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);
 222
 223         return 0;
 224 }
 225
 226 static int (*reloc_handlers[]) (struct module *me, uint32_t *location,
 227         Elf64_Addr v) = {
 228         [R_MIPS_NONE]           = apply_r_mips_none,
 229         [R_MIPS_32]             = apply_r_mips_32,
 230         [R_MIPS_26]             = apply_r_mips_26,
 231         [R_MIPS_HI16]           = apply_r_mips_hi16,
 232         [R_MIPS_LO16]           = apply_r_mips_lo16,
 233         [R_MIPS_64]             = apply_r_mips_64,
 234         [R_MIPS_HIGHER]         = apply_r_mips_higher,
 235         [R_MIPS_HIGHEST]        = apply_r_mips_highest
 236 };
 237
 238 int apply_relocate_add(Elf64_Shdr *sechdrs,
 239                        const char *strtab,
 240                        unsigned int symindex,
 241                        unsigned int relsec,
 242                        struct module *me)
 243 {
 244         Elf64_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
 245         Elf64_Sym *sym;
 246         uint32_t *location;
 247         unsigned int i;
 248         Elf64_Addr v;
 249         int res;
 250
 251         pr_debug("Applying relocate section %u to %u\n", relsec,
 252                sechdrs[relsec].sh_info);
 253
 254         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 255                 /* This is where to make the change */
 256                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 257                         + rel[i].r_offset;
 258                 /* This is the symbol it is referring to */
 259                 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr + rel[i].r_sym;
 260                 if (!sym->st_value) {
 261                         printk(KERN_WARNING "%s: Unknown symbol %s\n",
 262                                me->name, strtab + sym->st_name);
 263                         return -ENOENT;
 264                 }
 265
 266                 v = sym->st_value;
 267
 268                 res = reloc_handlers[rel[i].r_type](me, location, v);
 269                 if (res)
 270                         return res;
 271         }
 272
 273         return 0;
 274 }