1 /* 2 * Kernel module help for s390. 3 * 4 * S390 version 5 * Copyright IBM Corp. 2002, 2003 6 * Author(s): Arnd Bergmann (arndb@de.ibm.com) 7 * Martin Schwidefsky (schwidefsky@de.ibm.com) 8 * 9 * based on i386 version 10 * Copyright (C) 2001 Rusty Russell. 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License as published by 14 * the Free Software Foundation; either version 2 of the License, or 15 * (at your option) any later version. 16 * 17 * This program is distributed in the hope that it will be useful, 18 * but WITHOUT ANY WARRANTY; without even the implied warranty of 19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 20 * GNU General Public License for more details. 21 * 22 * You should have received a copy of the GNU General Public License 23 * along with this program; if not, write to the Free Software 24 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 25 */ 26 #include <linux/module.h> 27 #include <linux/elf.h> 28 #include <linux/vmalloc.h> 29 #include <linux/fs.h> 30 #include <linux/string.h> 31 #include <linux/kernel.h> 32 #include <linux/moduleloader.h> 33 #include <linux/bug.h> 34 35 #if 0 36 #define DEBUGP printk 37 #else 38 #define DEBUGP(fmt , ...) 39 #endif 40 41 #ifndef CONFIG_64BIT 42 #define PLT_ENTRY_SIZE 12 43 #else /* CONFIG_64BIT */ 44 #define PLT_ENTRY_SIZE 20 45 #endif /* CONFIG_64BIT */ 46 47 /* Free memory returned from module_alloc */ 48 void module_free(struct module *mod, void *module_region) 49 { 50 if (mod) { 51 vfree(mod->arch.syminfo); 52 mod->arch.syminfo = NULL; 53 } 54 vfree(module_region); 55 } 56 57 static void 58 check_rela(Elf_Rela *rela, struct module *me) 59 { 60 struct mod_arch_syminfo *info; 61 62 info = me->arch.syminfo + ELF_R_SYM (rela->r_info); 63 switch (ELF_R_TYPE (rela->r_info)) { 64 case R_390_GOT12: /* 12 bit GOT offset. */ 65 case R_390_GOT16: /* 16 bit GOT offset. */ 66 case R_390_GOT20: /* 20 bit GOT offset. */ 67 case R_390_GOT32: /* 32 bit GOT offset. */ 68 case R_390_GOT64: /* 64 bit GOT offset. */ 69 case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */ 70 case R_390_GOTPLT12: /* 12 bit offset to jump slot. */ 71 case R_390_GOTPLT16: /* 16 bit offset to jump slot. */ 72 case R_390_GOTPLT20: /* 20 bit offset to jump slot. */ 73 case R_390_GOTPLT32: /* 32 bit offset to jump slot. */ 74 case R_390_GOTPLT64: /* 64 bit offset to jump slot. */ 75 case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */ 76 if (info->got_offset == -1UL) { 77 info->got_offset = me->arch.got_size; 78 me->arch.got_size += sizeof(void*); 79 } 80 break; 81 case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */ 82 case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */ 83 case R_390_PLT32: /* 32 bit PC relative PLT address. */ 84 case R_390_PLT64: /* 64 bit PC relative PLT address. */ 85 case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */ 86 case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */ 87 case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */ 88 if (info->plt_offset == -1UL) { 89 info->plt_offset = me->arch.plt_size; 90 me->arch.plt_size += PLT_ENTRY_SIZE; 91 } 92 break; 93 case R_390_COPY: 94 case R_390_GLOB_DAT: 95 case R_390_JMP_SLOT: 96 case R_390_RELATIVE: 97 /* Only needed if we want to support loading of 98 modules linked with -shared. */ 99 break; 100 } 101 } 102 103 /* 104 * Account for GOT and PLT relocations. We can't add sections for 105 * got and plt but we can increase the core module size. 106 */ 107 int 108 module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, 109 char *secstrings, struct module *me) 110 { 111 Elf_Shdr *symtab; 112 Elf_Sym *symbols; 113 Elf_Rela *rela; 114 char *strings; 115 int nrela, i, j; 116 117 /* Find symbol table and string table. */ 118 symtab = NULL; 119 for (i = 0; i < hdr->e_shnum; i++) 120 switch (sechdrs[i].sh_type) { 121 case SHT_SYMTAB: 122 symtab = sechdrs + i; 123 break; 124 } 125 if (!symtab) { 126 printk(KERN_ERR "module %s: no symbol table\n", me->name); 127 return -ENOEXEC; 128 } 129 130 /* Allocate one syminfo structure per symbol. */ 131 me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym); 132 me->arch.syminfo = vmalloc(me->arch.nsyms * 133 sizeof(struct mod_arch_syminfo)); 134 if (!me->arch.syminfo) 135 return -ENOMEM; 136 symbols = (void *) hdr + symtab->sh_offset; 137 strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset; 138 for (i = 0; i < me->arch.nsyms; i++) { 139 if (symbols[i].st_shndx == SHN_UNDEF && 140 strcmp(strings + symbols[i].st_name, 141 "_GLOBAL_OFFSET_TABLE_") == 0) 142 /* "Define" it as absolute. */ 143 symbols[i].st_shndx = SHN_ABS; 144 me->arch.syminfo[i].got_offset = -1UL; 145 me->arch.syminfo[i].plt_offset = -1UL; 146 me->arch.syminfo[i].got_initialized = 0; 147 me->arch.syminfo[i].plt_initialized = 0; 148 } 149 150 /* Search for got/plt relocations. */ 151 me->arch.got_size = me->arch.plt_size = 0; 152 for (i = 0; i < hdr->e_shnum; i++) { 153 if (sechdrs[i].sh_type != SHT_RELA) 154 continue; 155 nrela = sechdrs[i].sh_size / sizeof(Elf_Rela); 156 rela = (void *) hdr + sechdrs[i].sh_offset; 157 for (j = 0; j < nrela; j++) 158 check_rela(rela + j, me); 159 } 160 161 /* Increase core size by size of got & plt and set start 162 offsets for got and plt. */ 163 me->core_size = ALIGN(me->core_size, 4); 164 me->arch.got_offset = me->core_size; 165 me->core_size += me->arch.got_size; 166 me->arch.plt_offset = me->core_size; 167 me->core_size += me->arch.plt_size; 168 return 0; 169 } 170 171 static int 172 apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, 173 struct module *me) 174 { 175 struct mod_arch_syminfo *info; 176 Elf_Addr loc, val; 177 int r_type, r_sym; 178 179 /* This is where to make the change */ 180 loc = base + rela->r_offset; 181 /* This is the symbol it is referring to. Note that all 182 undefined symbols have been resolved. */ 183 r_sym = ELF_R_SYM(rela->r_info); 184 r_type = ELF_R_TYPE(rela->r_info); 185 info = me->arch.syminfo + r_sym; 186 val = symtab[r_sym].st_value; 187 188 switch (r_type) { 189 case R_390_8: /* Direct 8 bit. */ 190 case R_390_12: /* Direct 12 bit. */ 191 case R_390_16: /* Direct 16 bit. */ 192 case R_390_20: /* Direct 20 bit. */ 193 case R_390_32: /* Direct 32 bit. */ 194 case R_390_64: /* Direct 64 bit. */ 195 val += rela->r_addend; 196 if (r_type == R_390_8) 197 *(unsigned char *) loc = val; 198 else if (r_type == R_390_12) 199 *(unsigned short *) loc = (val & 0xfff) | 200 (*(unsigned short *) loc & 0xf000); 201 else if (r_type == R_390_16) 202 *(unsigned short *) loc = val; 203 else if (r_type == R_390_20) 204 *(unsigned int *) loc = 205 (*(unsigned int *) loc & 0xf00000ff) | 206 (val & 0xfff) << 16 | (val & 0xff000) >> 4; 207 else if (r_type == R_390_32) 208 *(unsigned int *) loc = val; 209 else if (r_type == R_390_64) 210 *(unsigned long *) loc = val; 211 break; 212 case R_390_PC16: /* PC relative 16 bit. */ 213 case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */ 214 case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */ 215 case R_390_PC32: /* PC relative 32 bit. */ 216 case R_390_PC64: /* PC relative 64 bit. */ 217 val += rela->r_addend - loc; 218 if (r_type == R_390_PC16) 219 *(unsigned short *) loc = val; 220 else if (r_type == R_390_PC16DBL) 221 *(unsigned short *) loc = val >> 1; 222 else if (r_type == R_390_PC32DBL) 223 *(unsigned int *) loc = val >> 1; 224 else if (r_type == R_390_PC32) 225 *(unsigned int *) loc = val; 226 else if (r_type == R_390_PC64) 227 *(unsigned long *) loc = val; 228 break; 229 case R_390_GOT12: /* 12 bit GOT offset. */ 230 case R_390_GOT16: /* 16 bit GOT offset. */ 231 case R_390_GOT20: /* 20 bit GOT offset. */ 232 case R_390_GOT32: /* 32 bit GOT offset. */ 233 case R_390_GOT64: /* 64 bit GOT offset. */ 234 case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */ 235 case R_390_GOTPLT12: /* 12 bit offset to jump slot. */ 236 case R_390_GOTPLT20: /* 20 bit offset to jump slot. */ 237 case R_390_GOTPLT16: /* 16 bit offset to jump slot. */ 238 case R_390_GOTPLT32: /* 32 bit offset to jump slot. */ 239 case R_390_GOTPLT64: /* 64 bit offset to jump slot. */ 240 case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */ 241 if (info->got_initialized == 0) { 242 Elf_Addr *gotent; 243 244 gotent = me->module_core + me->arch.got_offset + 245 info->got_offset; 246 *gotent = val; 247 info->got_initialized = 1; 248 } 249 val = info->got_offset + rela->r_addend; 250 if (r_type == R_390_GOT12 || 251 r_type == R_390_GOTPLT12) 252 *(unsigned short *) loc = (val & 0xfff) | 253 (*(unsigned short *) loc & 0xf000); 254 else if (r_type == R_390_GOT16 || 255 r_type == R_390_GOTPLT16) 256 *(unsigned short *) loc = val; 257 else if (r_type == R_390_GOT20 || 258 r_type == R_390_GOTPLT20) 259 *(unsigned int *) loc = 260 (*(unsigned int *) loc & 0xf00000ff) | 261 (val & 0xfff) << 16 | (val & 0xff000) >> 4; 262 else if (r_type == R_390_GOT32 || 263 r_type == R_390_GOTPLT32) 264 *(unsigned int *) loc = val; 265 else if (r_type == R_390_GOTENT || 266 r_type == R_390_GOTPLTENT) 267 *(unsigned int *) loc = 268 (val + (Elf_Addr) me->module_core - loc) >> 1; 269 else if (r_type == R_390_GOT64 || 270 r_type == R_390_GOTPLT64) 271 *(unsigned long *) loc = val; 272 break; 273 case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */ 274 case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */ 275 case R_390_PLT32: /* 32 bit PC relative PLT address. */ 276 case R_390_PLT64: /* 64 bit PC relative PLT address. */ 277 case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */ 278 case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */ 279 case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */ 280 if (info->plt_initialized == 0) { 281 unsigned int *ip; 282 ip = me->module_core + me->arch.plt_offset + 283 info->plt_offset; 284 #ifndef CONFIG_64BIT 285 ip[0] = 0x0d105810; /* basr 1,0; l 1,6(1); br 1 */ 286 ip[1] = 0x100607f1; 287 ip[2] = val; 288 #else /* CONFIG_64BIT */ 289 ip[0] = 0x0d10e310; /* basr 1,0; lg 1,10(1); br 1 */ 290 ip[1] = 0x100a0004; 291 ip[2] = 0x07f10000; 292 ip[3] = (unsigned int) (val >> 32); 293 ip[4] = (unsigned int) val; 294 #endif /* CONFIG_64BIT */ 295 info->plt_initialized = 1; 296 } 297 if (r_type == R_390_PLTOFF16 || 298 r_type == R_390_PLTOFF32 || 299 r_type == R_390_PLTOFF64) 300 val = me->arch.plt_offset - me->arch.got_offset + 301 info->plt_offset + rela->r_addend; 302 else { 303 if (!((r_type == R_390_PLT16DBL && 304 val - loc + 0xffffUL < 0x1ffffeUL) || 305 (r_type == R_390_PLT32DBL && 306 val - loc + 0xffffffffULL < 0x1fffffffeULL))) 307 val = (Elf_Addr) me->module_core + 308 me->arch.plt_offset + 309 info->plt_offset; 310 val += rela->r_addend - loc; 311 } 312 if (r_type == R_390_PLT16DBL) 313 *(unsigned short *) loc = val >> 1; 314 else if (r_type == R_390_PLTOFF16) 315 *(unsigned short *) loc = val; 316 else if (r_type == R_390_PLT32DBL) 317 *(unsigned int *) loc = val >> 1; 318 else if (r_type == R_390_PLT32 || 319 r_type == R_390_PLTOFF32) 320 *(unsigned int *) loc = val; 321 else if (r_type == R_390_PLT64 || 322 r_type == R_390_PLTOFF64) 323 *(unsigned long *) loc = val; 324 break; 325 case R_390_GOTOFF16: /* 16 bit offset to GOT. */ 326 case R_390_GOTOFF32: /* 32 bit offset to GOT. */ 327 case R_390_GOTOFF64: /* 64 bit offset to GOT. */ 328 val = val + rela->r_addend - 329 ((Elf_Addr) me->module_core + me->arch.got_offset); 330 if (r_type == R_390_GOTOFF16) 331 *(unsigned short *) loc = val; 332 else if (r_type == R_390_GOTOFF32) 333 *(unsigned int *) loc = val; 334 else if (r_type == R_390_GOTOFF64) 335 *(unsigned long *) loc = val; 336 break; 337 case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */ 338 case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */ 339 val = (Elf_Addr) me->module_core + me->arch.got_offset + 340 rela->r_addend - loc; 341 if (r_type == R_390_GOTPC) 342 *(unsigned int *) loc = val; 343 else if (r_type == R_390_GOTPCDBL) 344 *(unsigned int *) loc = val >> 1; 345 break; 346 case R_390_COPY: 347 case R_390_GLOB_DAT: /* Create GOT entry. */ 348 case R_390_JMP_SLOT: /* Create PLT entry. */ 349 case R_390_RELATIVE: /* Adjust by program base. */ 350 /* Only needed if we want to support loading of 351 modules linked with -shared. */ 352 break; 353 default: 354 printk(KERN_ERR "module %s: Unknown relocation: %u\n", 355 me->name, r_type); 356 return -ENOEXEC; 357 } 358 return 0; 359 } 360 361 int 362 apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, 363 unsigned int symindex, unsigned int relsec, 364 struct module *me) 365 { 366 Elf_Addr base; 367 Elf_Sym *symtab; 368 Elf_Rela *rela; 369 unsigned long i, n; 370 int rc; 371 372 DEBUGP("Applying relocate section %u to %u\n", 373 relsec, sechdrs[relsec].sh_info); 374 base = sechdrs[sechdrs[relsec].sh_info].sh_addr; 375 symtab = (Elf_Sym *) sechdrs[symindex].sh_addr; 376 rela = (Elf_Rela *) sechdrs[relsec].sh_addr; 377 n = sechdrs[relsec].sh_size / sizeof(Elf_Rela); 378 379 for (i = 0; i < n; i++, rela++) { 380 rc = apply_rela(rela, base, symtab, me); 381 if (rc) 382 return rc; 383 } 384 return 0; 385 } 386 387 int module_finalize(const Elf_Ehdr *hdr, 388 const Elf_Shdr *sechdrs, 389 struct module *me) 390 { 391 vfree(me->arch.syminfo); 392 me->arch.syminfo = NULL; 393 return 0; 394 } 395