1 /*- 2 * Copyright (c) 2014-2015 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * Portions of this software were developed by Andrew Turner 6 * under sponsorship from the FreeBSD Foundation. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/types.h> 34 35 #include <stdlib.h> 36 37 #include "debug.h" 38 #include "rtld.h" 39 #include "rtld_printf.h" 40 41 /* 42 * It is possible for the compiler to emit relocations for unaligned data. 43 * We handle this situation with these inlines. 44 */ 45 #define RELOC_ALIGNED_P(x) \ 46 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) 47 48 /* 49 * This is not the correct prototype, but we only need it for 50 * a function pointer to a simple asm function. 51 */ 52 void *_rtld_tlsdesc(void *); 53 void *_rtld_tlsdesc_dynamic(void *); 54 55 void _exit(int); 56 57 void 58 init_pltgot(Obj_Entry *obj) 59 { 60 61 if (obj->pltgot != NULL) { 62 obj->pltgot[1] = (Elf_Addr) obj; 63 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 64 } 65 } 66 67 int 68 do_copy_relocations(Obj_Entry *dstobj) 69 { 70 const Obj_Entry *srcobj, *defobj; 71 const Elf_Rela *relalim; 72 const Elf_Rela *rela; 73 const Elf_Sym *srcsym; 74 const Elf_Sym *dstsym; 75 const void *srcaddr; 76 const char *name; 77 void *dstaddr; 78 SymLook req; 79 size_t size; 80 int res; 81 82 /* 83 * COPY relocs are invalid outside of the main program 84 */ 85 assert(dstobj->mainprog); 86 87 relalim = (const Elf_Rela *)((char *)dstobj->rela + 88 dstobj->relasize); 89 for (rela = dstobj->rela; rela < relalim; rela++) { 90 if (ELF_R_TYPE(rela->r_info) != R_AARCH64_COPY) 91 continue; 92 93 dstaddr = (void *)(dstobj->relocbase + rela->r_offset); 94 dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); 95 name = dstobj->strtab + dstsym->st_name; 96 size = dstsym->st_size; 97 98 symlook_init(&req, name); 99 req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)); 100 req.flags = SYMLOOK_EARLY; 101 102 for (srcobj = dstobj->next; srcobj != NULL; 103 srcobj = srcobj->next) { 104 res = symlook_obj(&req, srcobj); 105 if (res == 0) { 106 srcsym = req.sym_out; 107 defobj = req.defobj_out; 108 break; 109 } 110 } 111 if (srcobj == NULL) { 112 _rtld_error( 113 "Undefined symbol \"%s\" referenced from COPY relocation in %s", 114 name, dstobj->path); 115 return (-1); 116 } 117 118 srcaddr = (const void *)(defobj->relocbase + srcsym->st_value); 119 memcpy(dstaddr, srcaddr, size); 120 } 121 122 return (0); 123 } 124 125 struct tls_data { 126 int64_t index; 127 Obj_Entry *obj; 128 const Elf_Rela *rela; 129 }; 130 131 static struct tls_data * 132 reloc_tlsdesc_alloc(Obj_Entry *obj, const Elf_Rela *rela) 133 { 134 struct tls_data *tlsdesc; 135 136 tlsdesc = xmalloc(sizeof(struct tls_data)); 137 tlsdesc->index = -1; 138 tlsdesc->obj = obj; 139 tlsdesc->rela = rela; 140 141 return (tlsdesc); 142 } 143 144 /* 145 * Look up the symbol to find its tls index 146 */ 147 static int64_t 148 rtld_tlsdesc_handle_locked(struct tls_data *tlsdesc, int flags, 149 RtldLockState *lockstate) 150 { 151 const Elf_Rela *rela; 152 const Elf_Sym *def; 153 const Obj_Entry *defobj; 154 Obj_Entry *obj; 155 156 rela = tlsdesc->rela; 157 obj = tlsdesc->obj; 158 159 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, flags, NULL, 160 lockstate); 161 if (def == NULL) 162 rtld_die(); 163 164 tlsdesc->index = defobj->tlsoffset + def->st_value + rela->r_addend; 165 166 return (tlsdesc->index); 167 } 168 169 int64_t 170 rtld_tlsdesc_handle(struct tls_data *tlsdesc, int flags) 171 { 172 RtldLockState lockstate; 173 174 /* We have already found the index, return it */ 175 if (tlsdesc->index >= 0) 176 return (tlsdesc->index); 177 178 wlock_acquire(rtld_bind_lock, &lockstate); 179 /* tlsdesc->index may have been set by another thread */ 180 if (tlsdesc->index == -1) 181 rtld_tlsdesc_handle_locked(tlsdesc, flags, &lockstate); 182 lock_release(rtld_bind_lock, &lockstate); 183 184 return (tlsdesc->index); 185 } 186 187 /* 188 * Process the PLT relocations. 189 */ 190 int 191 reloc_plt(Obj_Entry *obj) 192 { 193 const Elf_Rela *relalim; 194 const Elf_Rela *rela; 195 196 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); 197 for (rela = obj->pltrela; rela < relalim; rela++) { 198 Elf_Addr *where; 199 200 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 201 202 switch(ELF_R_TYPE(rela->r_info)) { 203 case R_AARCH64_JUMP_SLOT: 204 *where += (Elf_Addr)obj->relocbase; 205 break; 206 case R_AARCH64_TLSDESC: 207 if (ELF_R_SYM(rela->r_info) == 0) { 208 where[0] = (Elf_Addr)_rtld_tlsdesc; 209 where[1] = obj->tlsoffset + rela->r_addend; 210 } else { 211 where[0] = (Elf_Addr)_rtld_tlsdesc_dynamic; 212 where[1] = (Elf_Addr)reloc_tlsdesc_alloc(obj, 213 rela); 214 } 215 break; 216 default: 217 _rtld_error("Unknown relocation type %u in PLT", 218 (unsigned int)ELF_R_TYPE(rela->r_info)); 219 return (-1); 220 } 221 } 222 223 return (0); 224 } 225 226 /* 227 * LD_BIND_NOW was set - force relocation for all jump slots 228 */ 229 int 230 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate) 231 { 232 const Obj_Entry *defobj; 233 const Elf_Rela *relalim; 234 const Elf_Rela *rela; 235 const Elf_Sym *def; 236 struct tls_data *tlsdesc; 237 238 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); 239 for (rela = obj->pltrela; rela < relalim; rela++) { 240 Elf_Addr *where; 241 242 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 243 switch(ELF_R_TYPE(rela->r_info)) { 244 case R_AARCH64_JUMP_SLOT: 245 def = find_symdef(ELF_R_SYM(rela->r_info), obj, 246 &defobj, SYMLOOK_IN_PLT | flags, NULL, lockstate); 247 if (def == NULL) { 248 dbg("reloc_jmpslots: sym not found"); 249 return (-1); 250 } 251 252 *where = (Elf_Addr)(defobj->relocbase + def->st_value); 253 break; 254 case R_AARCH64_TLSDESC: 255 if (ELF_R_SYM(rela->r_info) != 0) { 256 tlsdesc = (struct tls_data *)where[1]; 257 if (tlsdesc->index == -1) 258 rtld_tlsdesc_handle_locked(tlsdesc, 259 SYMLOOK_IN_PLT | flags, lockstate); 260 } 261 break; 262 default: 263 _rtld_error("Unknown relocation type %x in jmpslot", 264 (unsigned int)ELF_R_TYPE(rela->r_info)); 265 return (-1); 266 } 267 } 268 269 return (0); 270 } 271 272 int 273 reloc_iresolve(Obj_Entry *obj, struct Struct_RtldLockState *lockstate) 274 { 275 276 /* XXX not implemented */ 277 return (0); 278 } 279 280 int 281 reloc_gnu_ifunc(Obj_Entry *obj, int flags, 282 struct Struct_RtldLockState *lockstate) 283 { 284 285 /* XXX not implemented */ 286 return (0); 287 } 288 289 Elf_Addr 290 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, const Obj_Entry *defobj, 291 const Obj_Entry *obj, const Elf_Rel *rel) 292 { 293 294 assert(ELF_R_TYPE(rel->r_info) == R_AARCH64_JUMP_SLOT); 295 296 if (*where != target) 297 *where = target; 298 299 return target; 300 } 301 302 /* 303 * Process non-PLT relocations 304 */ 305 int 306 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags, 307 RtldLockState *lockstate) 308 { 309 const Obj_Entry *defobj; 310 const Elf_Rela *relalim; 311 const Elf_Rela *rela; 312 const Elf_Sym *def; 313 SymCache *cache; 314 Elf_Addr *where; 315 unsigned long symnum; 316 317 if ((flags & SYMLOOK_IFUNC) != 0) 318 /* XXX not implemented */ 319 return (0); 320 321 /* 322 * The dynamic loader may be called from a thread, we have 323 * limited amounts of stack available so we cannot use alloca(). 324 */ 325 if (obj == obj_rtld) 326 cache = NULL; 327 else 328 cache = calloc(obj->dynsymcount, sizeof(SymCache)); 329 /* No need to check for NULL here */ 330 331 relalim = (const Elf_Rela *)((caddr_t)obj->rela + obj->relasize); 332 for (rela = obj->rela; rela < relalim; rela++) { 333 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 334 symnum = ELF_R_SYM(rela->r_info); 335 336 switch (ELF_R_TYPE(rela->r_info)) { 337 case R_AARCH64_ABS64: 338 case R_AARCH64_GLOB_DAT: 339 def = find_symdef(symnum, obj, &defobj, flags, cache, 340 lockstate); 341 if (def == NULL) 342 return (-1); 343 344 *where = (Elf_Addr)defobj->relocbase + def->st_value + 345 rela->r_addend; 346 break; 347 case R_AARCH64_COPY: 348 /* 349 * These are deferred until all other relocations have 350 * been done. All we do here is make sure that the 351 * COPY relocation is not in a shared library. They 352 * are allowed only in executable files. 353 */ 354 if (!obj->mainprog) { 355 _rtld_error("%s: Unexpected R_AARCH64_COPY " 356 "relocation in shared library", obj->path); 357 return (-1); 358 } 359 break; 360 case R_AARCH64_TLS_TPREL64: 361 def = find_symdef(symnum, obj, &defobj, flags, cache, 362 lockstate); 363 if (def == NULL) 364 return (-1); 365 366 /* 367 * We lazily allocate offsets for static TLS as we 368 * see the first relocation that references the 369 * TLS block. This allows us to support (small 370 * amounts of) static TLS in dynamically loaded 371 * modules. If we run out of space, we generate an 372 * error. 373 */ 374 if (!defobj->tls_done) { 375 if (!allocate_tls_offset((Obj_Entry*) defobj)) { 376 _rtld_error( 377 "%s: No space available for static " 378 "Thread Local Storage", obj->path); 379 return (-1); 380 } 381 } 382 383 *where = def->st_value + rela->r_addend + 384 defobj->tlsoffset; 385 break; 386 case R_AARCH64_RELATIVE: 387 *where = (Elf_Addr)(obj->relocbase + rela->r_addend); 388 break; 389 default: 390 rtld_printf("%s: Unhandled relocation %lu\n", 391 obj->path, ELF_R_TYPE(rela->r_info)); 392 return (-1); 393 } 394 } 395 396 return (0); 397 } 398 399 void 400 allocate_initial_tls(Obj_Entry *objs) 401 { 402 Elf_Addr **tp; 403 404 /* 405 * Fix the size of the static TLS block by using the maximum 406 * offset allocated so far and adding a bit for dynamic modules to 407 * use. 408 */ 409 tls_static_space = tls_last_offset + tls_last_size + 410 RTLD_STATIC_TLS_EXTRA; 411 412 tp = (Elf_Addr **) allocate_tls(objs, NULL, TLS_TCB_SIZE, 16); 413 414 asm volatile("msr tpidr_el0, %0" : : "r"(tp)); 415 } 416