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