arch/avr32/kernel/module.c

   1 /*
   2  * AVR32-specific kernel module loader
   3  *
   4  * Copyright (C) 2005-2006 Atmel Corporation
   5  *
   6  * GOT initialization parts are based on the s390 version
   7  *   Copyright (C) 2002, 2003 IBM Deutschland Entwicklung GmbH,
   8  *                            IBM Corporation
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/moduleloader.h>
  16 #include <linux/module.h>
  17 #include <linux/kernel.h>
  18 #include <linux/elf.h>
  19 #include <linux/vmalloc.h>
  20
  21 void *module_alloc(unsigned long size)
  22 {
  23         if (size == 0)
  24                 return NULL;
  25         return vmalloc(size);
  26 }
  27
  28 void module_free(struct module *mod, void *module_region)
  29 {
  30         vfree(mod->arch.syminfo);
  31         mod->arch.syminfo = NULL;
  32
  33         vfree(module_region);
  34         /* FIXME: if module_region == mod->init_region, trim exception
  35          * table entries. */
  36 }
  37
  38 static inline int check_rela(Elf32_Rela *rela, struct module *module,
  39                              char *strings, Elf32_Sym *symbols)
  40 {
  41         struct mod_arch_syminfo *info;
  42
  43         info = module->arch.syminfo + ELF32_R_SYM(rela->r_info);
  44         switch (ELF32_R_TYPE(rela->r_info)) {
  45         case R_AVR32_GOT32:
  46         case R_AVR32_GOT16:
  47         case R_AVR32_GOT8:
  48         case R_AVR32_GOT21S:
  49         case R_AVR32_GOT18SW:   /* mcall */
  50         case R_AVR32_GOT16S:    /* ld.w */
  51                 if (rela->r_addend != 0) {
  52                         printk(KERN_ERR
  53                                "GOT relocation against %s at offset %u with addend\n",
  54                                strings + symbols[ELF32_R_SYM(rela->r_info)].st_name,
  55                                rela->r_offset);
  56                         return -ENOEXEC;
  57                 }
  58                 if (info->got_offset == -1UL) {
  59                         info->got_offset = module->arch.got_size;
  60                         module->arch.got_size += sizeof(void *);
  61                 }
  62                 pr_debug("GOT[%3lu] %s\n", info->got_offset,
  63                          strings + symbols[ELF32_R_SYM(rela->r_info)].st_name);
  64                 break;
  65         }
  66
  67         return 0;
  68 }
  69
  70 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
  71                               char *secstrings, struct module *module)
  72 {
  73         Elf32_Shdr *symtab;
  74         Elf32_Sym *symbols;
  75         Elf32_Rela *rela;
  76         char *strings;
  77         int nrela, i, j;
  78         int ret;
  79
  80         /* Find the symbol table */
  81         symtab = NULL;
  82         for (i = 0; i < hdr->e_shnum; i++)
  83                 switch (sechdrs[i].sh_type) {
  84                 case SHT_SYMTAB:
  85                         symtab = &sechdrs[i];
  86                         break;
  87                 }
  88         if (!symtab) {
  89                 printk(KERN_ERR "module %s: no symbol table\n", module->name);
  90                 return -ENOEXEC;
  91         }
  92
  93         /* Allocate room for one syminfo structure per symbol. */
  94         module->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
  95         module->arch.syminfo = vmalloc(module->arch.nsyms
  96                                    * sizeof(struct mod_arch_syminfo));
  97         if (!module->arch.syminfo)
  98                 return -ENOMEM;
  99
 100         symbols = (void *)hdr + symtab->sh_offset;
 101         strings = (void *)hdr + sechdrs[symtab->sh_link].sh_offset;
 102         for (i = 0; i < module->arch.nsyms; i++) {
 103                 if (symbols[i].st_shndx == SHN_UNDEF &&
 104                     strcmp(strings + symbols[i].st_name,
 105                            "_GLOBAL_OFFSET_TABLE_") == 0)
 106                         /* "Define" it as absolute. */
 107                         symbols[i].st_shndx = SHN_ABS;
 108                 module->arch.syminfo[i].got_offset = -1UL;
 109                 module->arch.syminfo[i].got_initialized = 0;
 110         }
 111
 112         /* Allocate GOT entries for symbols that need it. */
 113         module->arch.got_size = 0;
 114         for (i = 0; i < hdr->e_shnum; i++) {
 115                 if (sechdrs[i].sh_type != SHT_RELA)
 116                         continue;
 117                 nrela = sechdrs[i].sh_size / sizeof(Elf32_Rela);
 118                 rela = (void *)hdr + sechdrs[i].sh_offset;
 119                 for (j = 0; j < nrela; j++) {
 120                         ret = check_rela(rela + j, module,
 121                                          strings, symbols);
 122                         if (ret)
 123                                 goto out_free_syminfo;
 124                 }
 125         }
 126
 127         /*
 128          * Increase core size to make room for GOT and set start
 129          * offset for GOT.
 130          */
 131         module->core_size = ALIGN(module->core_size, 4);
 132         module->arch.got_offset = module->core_size;
 133         module->core_size += module->arch.got_size;
 134
 135         return 0;
 136
 137 out_free_syminfo:
 138         vfree(module->arch.syminfo);
 139         module->arch.syminfo = NULL;
 140
 141         return ret;
 142 }
 143
 144 static inline int reloc_overflow(struct module *module, const char *reloc_name,
 145                                  Elf32_Addr relocation)
 146 {
 147         printk(KERN_ERR "module %s: Value %lx does not fit relocation %s\n",
 148                module->name, (unsigned long)relocation, reloc_name);
 149         return -ENOEXEC;
 150 }
 151
 152 #define get_u16(loc)            (*((uint16_t *)loc))
 153 #define put_u16(loc, val)       (*((uint16_t *)loc) = (val))
 154
 155 int apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
 156                        unsigned int symindex, unsigned int relindex,
 157                        struct module *module)
 158 {
 159         Elf32_Shdr *symsec = sechdrs + symindex;
 160         Elf32_Shdr *relsec = sechdrs + relindex;
 161         Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
 162         Elf32_Rela *rel = (void *)relsec->sh_addr;
 163         unsigned int i;
 164         int ret = 0;
 165
 166         for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rela); i++, rel++) {
 167                 struct mod_arch_syminfo *info;
 168                 Elf32_Sym *sym;
 169                 Elf32_Addr relocation;
 170                 uint32_t *location;
 171                 uint32_t value;
 172
 173                 location = (void *)dstsec->sh_addr + rel->r_offset;
 174                 sym = (Elf32_Sym *)symsec->sh_addr + ELF32_R_SYM(rel->r_info);
 175                 relocation = sym->st_value + rel->r_addend;
 176
 177                 info = module->arch.syminfo + ELF32_R_SYM(rel->r_info);
 178
 179                 /* Initialize GOT entry if necessary */
 180                 switch (ELF32_R_TYPE(rel->r_info)) {
 181                 case R_AVR32_GOT32:
 182                 case R_AVR32_GOT16:
 183                 case R_AVR32_GOT8:
 184                 case R_AVR32_GOT21S:
 185                 case R_AVR32_GOT18SW:
 186                 case R_AVR32_GOT16S:
 187                         if (!info->got_initialized) {
 188                                 Elf32_Addr *gotent;
 189
 190                                 gotent = (module->module_core
 191                                           + module->arch.got_offset
 192                                           + info->got_offset);
 193                                 *gotent = relocation;
 194                                 info->got_initialized = 1;
 195                         }
 196
 197                         relocation = info->got_offset;
 198                         break;
 199                 }
 200
 201                 switch (ELF32_R_TYPE(rel->r_info)) {
 202                 case R_AVR32_32:
 203                 case R_AVR32_32_CPENT:
 204                         *location = relocation;
 205                         break;
 206                 case R_AVR32_22H_PCREL:
 207                         relocation -= (Elf32_Addr)location;
 208                         if ((relocation & 0xffe00001) != 0
 209                             && (relocation & 0xffc00001) != 0xffc00000)
 210                                 return reloc_overflow(module,
 211                                                       "R_AVR32_22H_PCREL",
 212                                                       relocation);
 213                         relocation >>= 1;
 214
 215                         value = *location;
 216                         value = ((value & 0xe1ef0000)
 217                                  | (relocation & 0xffff)
 218                                  | ((relocation & 0x10000) << 4)
 219                                  | ((relocation & 0x1e0000) << 8));
 220                         *location = value;
 221                         break;
 222                 case R_AVR32_11H_PCREL:
 223                         relocation -= (Elf32_Addr)location;
 224                         if ((relocation & 0xfffffc01) != 0
 225                             && (relocation & 0xfffff801) != 0xfffff800)
 226                                 return reloc_overflow(module,
 227                                                       "R_AVR32_11H_PCREL",
 228                                                       relocation);
 229                         value = get_u16(location);
 230                         value = ((value & 0xf00c)
 231                                  | ((relocation & 0x1fe) << 3)
 232                                  | ((relocation & 0x600) >> 9));
 233                         put_u16(location, value);
 234                         break;
 235                 case R_AVR32_9H_PCREL:
 236                         relocation -= (Elf32_Addr)location;
 237                         if ((relocation & 0xffffff01) != 0
 238                             && (relocation & 0xfffffe01) != 0xfffffe00)
 239                                 return reloc_overflow(module,
 240                                                       "R_AVR32_9H_PCREL",
 241                                                       relocation);
 242                         value = get_u16(location);
 243                         value = ((value & 0xf00f)
 244                                  | ((relocation & 0x1fe) << 3));
 245                         put_u16(location, value);
 246                         break;
 247                 case R_AVR32_9UW_PCREL:
 248                         relocation -= ((Elf32_Addr)location) & 0xfffffffc;
 249                         if ((relocation & 0xfffffc03) != 0)
 250                                 return reloc_overflow(module,
 251                                                       "R_AVR32_9UW_PCREL",
 252                                                       relocation);
 253                         value = get_u16(location);
 254                         value = ((value & 0xf80f)
 255                                  | ((relocation & 0x1fc) << 2));
 256                         put_u16(location, value);
 257                         break;
 258                 case R_AVR32_GOTPC:
 259                         /*
 260                          * R6 = PC - (PC - GOT)
 261                          *
 262                          * At this point, relocation contains the
 263                          * value of PC.  Just subtract the value of
 264                          * GOT, and we're done.
 265                          */
 266                         pr_debug("GOTPC: PC=0x%x, got_offset=0x%lx, core=0x%p\n",
 267                                  relocation, module->arch.got_offset,
 268                                  module->module_core);
 269                         relocation -= ((unsigned long)module->module_core
 270                                        + module->arch.got_offset);
 271                         *location = relocation;
 272                         break;
 273                 case R_AVR32_GOT18SW:
 274                         if ((relocation & 0xfffe0003) != 0
 275                             && (relocation & 0xfffc0003) != 0xffff0000)
 276                                 return reloc_overflow(module, "R_AVR32_GOT18SW",
 277                                                      relocation);
 278                         relocation >>= 2;
 279                         /* fall through */
 280                 case R_AVR32_GOT16S:
 281                         if ((relocation & 0xffff8000) != 0
 282                             && (relocation & 0xffff0000) != 0xffff0000)
 283                                 return reloc_overflow(module, "R_AVR32_GOT16S",
 284                                                       relocation);
 285                         pr_debug("GOT reloc @ 0x%x -> %u\n",
 286                                  rel->r_offset, relocation);
 287                         value = *location;
 288                         value = ((value & 0xffff0000)
 289                                  | (relocation & 0xffff));
 290                         *location = value;
 291                         break;
 292
 293                 default:
 294                         printk(KERN_ERR "module %s: Unknown relocation: %u\n",
 295                                module->name, ELF32_R_TYPE(rel->r_info));
 296                         return -ENOEXEC;
 297                 }
 298         }
 299
 300         return ret;
 301 }
 302
 303 int apply_relocate(Elf32_Shdr *sechdrs, const char *strtab,
 304                    unsigned int symindex, unsigned int relindex,
 305                    struct module *module)
 306 {
 307         printk(KERN_ERR "module %s: REL relocations are not supported\n",
 308                 module->name);
 309         return -ENOEXEC;
 310 }
 311
 312 int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
 313                     struct module *module)
 314 {
 315         vfree(module->arch.syminfo);
 316         module->arch.syminfo = NULL;
 317
 318         return 0;
 319 }
 320
 321 void module_arch_cleanup(struct module *module)
 322 {
 323
 324 }