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_arch_freeing_init(struct module *mod)
  23 {
  24         vfree(mod->arch.syminfo);
  25         mod->arch.syminfo = NULL;
  26 }
  27
  28 static inline int check_rela(Elf32_Rela *rela, struct module *module,
  29                              char *strings, Elf32_Sym *symbols)
  30 {
  31         struct mod_arch_syminfo *info;
  32
  33         info = module->arch.syminfo + ELF32_R_SYM(rela->r_info);
  34         switch (ELF32_R_TYPE(rela->r_info)) {
  35         case R_AVR32_GOT32:
  36         case R_AVR32_GOT16:
  37         case R_AVR32_GOT8:
  38         case R_AVR32_GOT21S:
  39         case R_AVR32_GOT18SW:   /* mcall */
  40         case R_AVR32_GOT16S:    /* ld.w */
  41                 if (rela->r_addend != 0) {
  42                         printk(KERN_ERR
  43                                "GOT relocation against %s at offset %u with addend\n",
  44                                strings + symbols[ELF32_R_SYM(rela->r_info)].st_name,
  45                                rela->r_offset);
  46                         return -ENOEXEC;
  47                 }
  48                 if (info->got_offset == -1UL) {
  49                         info->got_offset = module->arch.got_size;
  50                         module->arch.got_size += sizeof(void *);
  51                 }
  52                 pr_debug("GOT[%3lu] %s\n", info->got_offset,
  53                          strings + symbols[ELF32_R_SYM(rela->r_info)].st_name);
  54                 break;
  55         }
  56
  57         return 0;
  58 }
  59
  60 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
  61                               char *secstrings, struct module *module)
  62 {
  63         Elf32_Shdr *symtab;
  64         Elf32_Sym *symbols;
  65         Elf32_Rela *rela;
  66         char *strings;
  67         int nrela, i, j;
  68         int ret;
  69
  70         /* Find the symbol table */
  71         symtab = NULL;
  72         for (i = 0; i < hdr->e_shnum; i++)
  73                 switch (sechdrs[i].sh_type) {
  74                 case SHT_SYMTAB:
  75                         symtab = &sechdrs[i];
  76                         break;
  77                 }
  78         if (!symtab) {
  79                 printk(KERN_ERR "module %s: no symbol table\n", module->name);
  80                 return -ENOEXEC;
  81         }
  82
  83         /* Allocate room for one syminfo structure per symbol. */
  84         module->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
  85         module->arch.syminfo = vmalloc(module->arch.nsyms
  86                                    * sizeof(struct mod_arch_syminfo));
  87         if (!module->arch.syminfo)
  88                 return -ENOMEM;
  89
  90         symbols = (void *)hdr + symtab->sh_offset;
  91         strings = (void *)hdr + sechdrs[symtab->sh_link].sh_offset;
  92         for (i = 0; i < module->arch.nsyms; i++) {
  93                 if (symbols[i].st_shndx == SHN_UNDEF &&
  94                     strcmp(strings + symbols[i].st_name,
  95                            "_GLOBAL_OFFSET_TABLE_") == 0)
  96                         /* "Define" it as absolute. */
  97                         symbols[i].st_shndx = SHN_ABS;
  98                 module->arch.syminfo[i].got_offset = -1UL;
  99                 module->arch.syminfo[i].got_initialized = 0;
 100         }
 101
 102         /* Allocate GOT entries for symbols that need it. */
 103         module->arch.got_size = 0;
 104         for (i = 0; i < hdr->e_shnum; i++) {
 105                 if (sechdrs[i].sh_type != SHT_RELA)
 106                         continue;
 107                 nrela = sechdrs[i].sh_size / sizeof(Elf32_Rela);
 108                 rela = (void *)hdr + sechdrs[i].sh_offset;
 109                 for (j = 0; j < nrela; j++) {
 110                         ret = check_rela(rela + j, module,
 111                                          strings, symbols);
 112                         if (ret)
 113                                 goto out_free_syminfo;
 114                 }
 115         }
 116
 117         /*
 118          * Increase core size to make room for GOT and set start
 119          * offset for GOT.
 120          */
 121         module->core_size = ALIGN(module->core_size, 4);
 122         module->arch.got_offset = module->core_size;
 123         module->core_size += module->arch.got_size;
 124
 125         return 0;
 126
 127 out_free_syminfo:
 128         vfree(module->arch.syminfo);
 129         module->arch.syminfo = NULL;
 130
 131         return ret;
 132 }
 133
 134 static inline int reloc_overflow(struct module *module, const char *reloc_name,
 135                                  Elf32_Addr relocation)
 136 {
 137         printk(KERN_ERR "module %s: Value %lx does not fit relocation %s\n",
 138                module->name, (unsigned long)relocation, reloc_name);
 139         return -ENOEXEC;
 140 }
 141
 142 #define get_u16(loc)            (*((uint16_t *)loc))
 143 #define put_u16(loc, val)       (*((uint16_t *)loc) = (val))
 144
 145 int apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
 146                        unsigned int symindex, unsigned int relindex,
 147                        struct module *module)
 148 {
 149         Elf32_Shdr *symsec = sechdrs + symindex;
 150         Elf32_Shdr *relsec = sechdrs + relindex;
 151         Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
 152         Elf32_Rela *rel = (void *)relsec->sh_addr;
 153         unsigned int i;
 154         int ret = 0;
 155
 156         for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rela); i++, rel++) {
 157                 struct mod_arch_syminfo *info;
 158                 Elf32_Sym *sym;
 159                 Elf32_Addr relocation;
 160                 uint32_t *location;
 161                 uint32_t value;
 162
 163                 location = (void *)dstsec->sh_addr + rel->r_offset;
 164                 sym = (Elf32_Sym *)symsec->sh_addr + ELF32_R_SYM(rel->r_info);
 165                 relocation = sym->st_value + rel->r_addend;
 166
 167                 info = module->arch.syminfo + ELF32_R_SYM(rel->r_info);
 168
 169                 /* Initialize GOT entry if necessary */
 170                 switch (ELF32_R_TYPE(rel->r_info)) {
 171                 case R_AVR32_GOT32:
 172                 case R_AVR32_GOT16:
 173                 case R_AVR32_GOT8:
 174                 case R_AVR32_GOT21S:
 175                 case R_AVR32_GOT18SW:
 176                 case R_AVR32_GOT16S:
 177                         if (!info->got_initialized) {
 178                                 Elf32_Addr *gotent;
 179
 180                                 gotent = (module->module_core
 181                                           + module->arch.got_offset
 182                                           + info->got_offset);
 183                                 *gotent = relocation;
 184                                 info->got_initialized = 1;
 185                         }
 186
 187                         relocation = info->got_offset;
 188                         break;
 189                 }
 190
 191                 switch (ELF32_R_TYPE(rel->r_info)) {
 192                 case R_AVR32_32:
 193                 case R_AVR32_32_CPENT:
 194                         *location = relocation;
 195                         break;
 196                 case R_AVR32_22H_PCREL:
 197                         relocation -= (Elf32_Addr)location;
 198                         if ((relocation & 0xffe00001) != 0
 199                             && (relocation & 0xffc00001) != 0xffc00000)
 200                                 return reloc_overflow(module,
 201                                                       "R_AVR32_22H_PCREL",
 202                                                       relocation);
 203                         relocation >>= 1;
 204
 205                         value = *location;
 206                         value = ((value & 0xe1ef0000)
 207                                  | (relocation & 0xffff)
 208                                  | ((relocation & 0x10000) << 4)
 209                                  | ((relocation & 0x1e0000) << 8));
 210                         *location = value;
 211                         break;
 212                 case R_AVR32_11H_PCREL:
 213                         relocation -= (Elf32_Addr)location;
 214                         if ((relocation & 0xfffffc01) != 0
 215                             && (relocation & 0xfffff801) != 0xfffff800)
 216                                 return reloc_overflow(module,
 217                                                       "R_AVR32_11H_PCREL",
 218                                                       relocation);
 219                         value = get_u16(location);
 220                         value = ((value & 0xf00c)
 221                                  | ((relocation & 0x1fe) << 3)
 222                                  | ((relocation & 0x600) >> 9));
 223                         put_u16(location, value);
 224                         break;
 225                 case R_AVR32_9H_PCREL:
 226                         relocation -= (Elf32_Addr)location;
 227                         if ((relocation & 0xffffff01) != 0
 228                             && (relocation & 0xfffffe01) != 0xfffffe00)
 229                                 return reloc_overflow(module,
 230                                                       "R_AVR32_9H_PCREL",
 231                                                       relocation);
 232                         value = get_u16(location);
 233                         value = ((value & 0xf00f)
 234                                  | ((relocation & 0x1fe) << 3));
 235                         put_u16(location, value);
 236                         break;
 237                 case R_AVR32_9UW_PCREL:
 238                         relocation -= ((Elf32_Addr)location) & 0xfffffffc;
 239                         if ((relocation & 0xfffffc03) != 0)
 240                                 return reloc_overflow(module,
 241                                                       "R_AVR32_9UW_PCREL",
 242                                                       relocation);
 243                         value = get_u16(location);
 244                         value = ((value & 0xf80f)
 245                                  | ((relocation & 0x1fc) << 2));
 246                         put_u16(location, value);
 247                         break;
 248                 case R_AVR32_GOTPC:
 249                         /*
 250                          * R6 = PC - (PC - GOT)
 251                          *
 252                          * At this point, relocation contains the
 253                          * value of PC.  Just subtract the value of
 254                          * GOT, and we're done.
 255                          */
 256                         pr_debug("GOTPC: PC=0x%x, got_offset=0x%lx, core=0x%p\n",
 257                                  relocation, module->arch.got_offset,
 258                                  module->module_core);
 259                         relocation -= ((unsigned long)module->module_core
 260                                        + module->arch.got_offset);
 261                         *location = relocation;
 262                         break;
 263                 case R_AVR32_GOT18SW:
 264                         if ((relocation & 0xfffe0003) != 0
 265                             && (relocation & 0xfffc0000) != 0xfffc0000)
 266                                 return reloc_overflow(module, "R_AVR32_GOT18SW",
 267                                                      relocation);
 268                         relocation >>= 2;
 269                         /* fall through */
 270                 case R_AVR32_GOT16S:
 271                         if ((relocation & 0xffff8000) != 0
 272                             && (relocation & 0xffff0000) != 0xffff0000)
 273                                 return reloc_overflow(module, "R_AVR32_GOT16S",
 274                                                       relocation);
 275                         pr_debug("GOT reloc @ 0x%x -> %u\n",
 276                                  rel->r_offset, relocation);
 277                         value = *location;
 278                         value = ((value & 0xffff0000)
 279                                  | (relocation & 0xffff));
 280                         *location = value;
 281                         break;
 282
 283                 default:
 284                         printk(KERN_ERR "module %s: Unknown relocation: %u\n",
 285                                module->name, ELF32_R_TYPE(rel->r_info));
 286                         return -ENOEXEC;
 287                 }
 288         }
 289
 290         return ret;
 291 }