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