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/bug.h>
  16 #include <linux/elf.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/moduleloader.h>
  20 #include <linux/vmalloc.h>
  21
  22 void *module_alloc(unsigned long size)
  23 {
  24         if (size == 0)
  25                 return NULL;
  26         return vmalloc(size);
  27 }
  28
  29 void module_free(struct module *mod, void *module_region)
  30 {
  31         vfree(mod->arch.syminfo);
  32         mod->arch.syminfo = NULL;
  33
  34         vfree(module_region);
  35         /* FIXME: if module_region == mod->init_region, trim exception
  36          * table entries. */
  37 }
  38
  39 static inline int check_rela(Elf32_Rela *rela, struct module *module,
  40                              char *strings, Elf32_Sym *symbols)
  41 {
  42         struct mod_arch_syminfo *info;
  43
  44         info = module->arch.syminfo + ELF32_R_SYM(rela->r_info);
  45         switch (ELF32_R_TYPE(rela->r_info)) {
  46         case R_AVR32_GOT32:
  47         case R_AVR32_GOT16:
  48         case R_AVR32_GOT8:
  49         case R_AVR32_GOT21S:
  50         case R_AVR32_GOT18SW:   /* mcall */
  51         case R_AVR32_GOT16S:    /* ld.w */
  52                 if (rela->r_addend != 0) {
  53                         printk(KERN_ERR
  54                                "GOT relocation against %s at offset %u with addend\n",
  55                                strings + symbols[ELF32_R_SYM(rela->r_info)].st_name,
  56                                rela->r_offset);
  57                         return -ENOEXEC;
  58                 }
  59                 if (info->got_offset == -1UL) {
  60                         info->got_offset = module->arch.got_size;
  61                         module->arch.got_size += sizeof(void *);
  62                 }
  63                 pr_debug("GOT[%3lu] %s\n", info->got_offset,
  64                          strings + symbols[ELF32_R_SYM(rela->r_info)].st_name);
  65                 break;
  66         }
  67
  68         return 0;
  69 }
  70
  71 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
  72                               char *secstrings, struct module *module)
  73 {
  74         Elf32_Shdr *symtab;
  75         Elf32_Sym *symbols;
  76         Elf32_Rela *rela;
  77         char *strings;
  78         int nrela, i, j;
  79         int ret;
  80
  81         /* Find the symbol table */
  82         symtab = NULL;
  83         for (i = 0; i < hdr->e_shnum; i++)
  84                 switch (sechdrs[i].sh_type) {
  85                 case SHT_SYMTAB:
  86                         symtab = &sechdrs[i];
  87                         break;
  88                 }
  89         if (!symtab) {
  90                 printk(KERN_ERR "module %s: no symbol table\n", module->name);
  91                 return -ENOEXEC;
  92         }
  93
  94         /* Allocate room for one syminfo structure per symbol. */
  95         module->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
  96         module->arch.syminfo = vmalloc(module->arch.nsyms
  97                                    * sizeof(struct mod_arch_syminfo));
  98         if (!module->arch.syminfo)
  99                 return -ENOMEM;
 100
 101         symbols = (void *)hdr + symtab->sh_offset;
 102         strings = (void *)hdr + sechdrs[symtab->sh_link].sh_offset;
 103         for (i = 0; i < module->arch.nsyms; i++) {
 104                 if (symbols[i].st_shndx == SHN_UNDEF &&
 105                     strcmp(strings + symbols[i].st_name,
 106                            "_GLOBAL_OFFSET_TABLE_") == 0)
 107                         /* "Define" it as absolute. */
 108                         symbols[i].st_shndx = SHN_ABS;
 109                 module->arch.syminfo[i].got_offset = -1UL;
 110                 module->arch.syminfo[i].got_initialized = 0;
 111         }
 112
 113         /* Allocate GOT entries for symbols that need it. */
 114         module->arch.got_size = 0;
 115         for (i = 0; i < hdr->e_shnum; i++) {
 116                 if (sechdrs[i].sh_type != SHT_RELA)
 117                         continue;
 118                 nrela = sechdrs[i].sh_size / sizeof(Elf32_Rela);
 119                 rela = (void *)hdr + sechdrs[i].sh_offset;
 120                 for (j = 0; j < nrela; j++) {
 121                         ret = check_rela(rela + j, module,
 122                                          strings, symbols);
 123                         if (ret)
 124                                 goto out_free_syminfo;
 125                 }
 126         }
 127
 128         /*
 129          * Increase core size to make room for GOT and set start
 130          * offset for GOT.
 131          */
 132         module->core_size = ALIGN(module->core_size, 4);
 133         module->arch.got_offset = module->core_size;
 134         module->core_size += module->arch.got_size;
 135
 136         return 0;
 137
 138 out_free_syminfo:
 139         vfree(module->arch.syminfo);
 140         module->arch.syminfo = NULL;
 141
 142         return ret;
 143 }
 144
 145 static inline int reloc_overflow(struct module *module, const char *reloc_name,
 146                                  Elf32_Addr relocation)
 147 {
 148         printk(KERN_ERR "module %s: Value %lx does not fit relocation %s\n",
 149                module->name, (unsigned long)relocation, reloc_name);
 150         return -ENOEXEC;
 151 }
 152
 153 #define get_u16(loc)            (*((uint16_t *)loc))
 154 #define put_u16(loc, val)       (*((uint16_t *)loc) = (val))
 155
 156 int apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
 157                        unsigned int symindex, unsigned int relindex,
 158                        struct module *module)
 159 {
 160         Elf32_Shdr *symsec = sechdrs + symindex;
 161         Elf32_Shdr *relsec = sechdrs + relindex;
 162         Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
 163         Elf32_Rela *rel = (void *)relsec->sh_addr;
 164         unsigned int i;
 165         int ret = 0;
 166
 167         for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rela); i++, rel++) {
 168                 struct mod_arch_syminfo *info;
 169                 Elf32_Sym *sym;
 170                 Elf32_Addr relocation;
 171                 uint32_t *location;
 172                 uint32_t value;
 173
 174                 location = (void *)dstsec->sh_addr + rel->r_offset;
 175                 sym = (Elf32_Sym *)symsec->sh_addr + ELF32_R_SYM(rel->r_info);
 176                 relocation = sym->st_value + rel->r_addend;
 177
 178                 info = module->arch.syminfo + ELF32_R_SYM(rel->r_info);
 179
 180                 /* Initialize GOT entry if necessary */
 181                 switch (ELF32_R_TYPE(rel->r_info)) {
 182                 case R_AVR32_GOT32:
 183                 case R_AVR32_GOT16:
 184                 case R_AVR32_GOT8:
 185                 case R_AVR32_GOT21S:
 186                 case R_AVR32_GOT18SW:
 187                 case R_AVR32_GOT16S:
 188                         if (!info->got_initialized) {
 189                                 Elf32_Addr *gotent;
 190
 191                                 gotent = (module->module_core
 192                                           + module->arch.got_offset
 193                                           + info->got_offset);
 194                                 *gotent = relocation;
 195                                 info->got_initialized = 1;
 196                         }
 197
 198                         relocation = info->got_offset;
 199                         break;
 200                 }
 201
 202                 switch (ELF32_R_TYPE(rel->r_info)) {
 203                 case R_AVR32_32:
 204                 case R_AVR32_32_CPENT:
 205                         *location = relocation;
 206                         break;
 207                 case R_AVR32_22H_PCREL:
 208                         relocation -= (Elf32_Addr)location;
 209                         if ((relocation & 0xffe00001) != 0
 210                             && (relocation & 0xffc00001) != 0xffc00000)
 211                                 return reloc_overflow(module,
 212                                                       "R_AVR32_22H_PCREL",
 213                                                       relocation);
 214                         relocation >>= 1;
 215
 216                         value = *location;
 217                         value = ((value & 0xe1ef0000)
 218                                  | (relocation & 0xffff)
 219                                  | ((relocation & 0x10000) << 4)
 220                                  | ((relocation & 0x1e0000) << 8));
 221                         *location = value;
 222                         break;
 223                 case R_AVR32_11H_PCREL:
 224                         relocation -= (Elf32_Addr)location;
 225                         if ((relocation & 0xfffffc01) != 0
 226                             && (relocation & 0xfffff801) != 0xfffff800)
 227                                 return reloc_overflow(module,
 228                                                       "R_AVR32_11H_PCREL",
 229                                                       relocation);
 230                         value = get_u16(location);
 231                         value = ((value & 0xf00c)
 232                                  | ((relocation & 0x1fe) << 3)
 233                                  | ((relocation & 0x600) >> 9));
 234                         put_u16(location, value);
 235                         break;
 236                 case R_AVR32_9H_PCREL:
 237                         relocation -= (Elf32_Addr)location;
 238                         if ((relocation & 0xffffff01) != 0
 239                             && (relocation & 0xfffffe01) != 0xfffffe00)
 240                                 return reloc_overflow(module,
 241                                                       "R_AVR32_9H_PCREL",
 242                                                       relocation);
 243                         value = get_u16(location);
 244                         value = ((value & 0xf00f)
 245                                  | ((relocation & 0x1fe) << 3));
 246                         put_u16(location, value);
 247                         break;
 248                 case R_AVR32_9UW_PCREL:
 249                         relocation -= ((Elf32_Addr)location) & 0xfffffffc;
 250                         if ((relocation & 0xfffffc03) != 0)
 251                                 return reloc_overflow(module,
 252                                                       "R_AVR32_9UW_PCREL",
 253                                                       relocation);
 254                         value = get_u16(location);
 255                         value = ((value & 0xf80f)
 256                                  | ((relocation & 0x1fc) << 2));
 257                         put_u16(location, value);
 258                         break;
 259                 case R_AVR32_GOTPC:
 260                         /*
 261                          * R6 = PC - (PC - GOT)
 262                          *
 263                          * At this point, relocation contains the
 264                          * value of PC.  Just subtract the value of
 265                          * GOT, and we're done.
 266                          */
 267                         pr_debug("GOTPC: PC=0x%x, got_offset=0x%lx, core=0x%p\n",
 268                                  relocation, module->arch.got_offset,
 269                                  module->module_core);
 270                         relocation -= ((unsigned long)module->module_core
 271                                        + module->arch.got_offset);
 272                         *location = relocation;
 273                         break;
 274                 case R_AVR32_GOT18SW:
 275                         if ((relocation & 0xfffe0003) != 0
 276                             && (relocation & 0xfffc0003) != 0xffff0000)
 277                                 return reloc_overflow(module, "R_AVR32_GOT18SW",
 278                                                      relocation);
 279                         relocation >>= 2;
 280                         /* fall through */
 281                 case R_AVR32_GOT16S:
 282                         if ((relocation & 0xffff8000) != 0
 283                             && (relocation & 0xffff0000) != 0xffff0000)
 284                                 return reloc_overflow(module, "R_AVR32_GOT16S",
 285                                                       relocation);
 286                         pr_debug("GOT reloc @ 0x%x -> %u\n",
 287                                  rel->r_offset, relocation);
 288                         value = *location;
 289                         value = ((value & 0xffff0000)
 290                                  | (relocation & 0xffff));
 291                         *location = value;
 292                         break;
 293
 294                 default:
 295                         printk(KERN_ERR "module %s: Unknown relocation: %u\n",
 296                                module->name, ELF32_R_TYPE(rel->r_info));
 297                         return -ENOEXEC;
 298                 }
 299         }
 300
 301         return ret;
 302 }
 303
 304 int apply_relocate(Elf32_Shdr *sechdrs, const char *strtab,
 305                    unsigned int symindex, unsigned int relindex,
 306                    struct module *module)
 307 {
 308         printk(KERN_ERR "module %s: REL relocations are not supported\n",
 309                 module->name);
 310         return -ENOEXEC;
 311 }
 312
 313 int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
 314                     struct module *module)
 315 {
 316         vfree(module->arch.syminfo);
 317         module->arch.syminfo = NULL;
 318
 319         return module_bug_finalize(hdr, sechdrs, module);
 320 }
 321
 322 void module_arch_cleanup(struct module *module)
 323 {
 324         module_bug_cleanup(module);
 325 }