mdreloc.c revision 1.38
1 /* $NetBSD: mdreloc.c,v 1.38 2014/08/25 20:40:52 joerg Exp $ */ 2 3 #include <sys/cdefs.h> 4 #ifndef lint 5 __RCSID("$NetBSD: mdreloc.c,v 1.38 2014/08/25 20:40:52 joerg Exp $"); 6 #endif /* not lint */ 7 8 #include <sys/types.h> 9 #include <string.h> 10 11 #include "debug.h" 12 #include "rtld.h" 13 14 void _rtld_bind_start(void); 15 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 16 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 17 18 void 19 _rtld_setup_pltgot(const Obj_Entry *obj) 20 { 21 obj->pltgot[1] = (Elf_Addr) obj; 22 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 23 } 24 25 void 26 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 27 { 28 const Elf_Rel *rel = 0, *rellim; 29 Elf_Addr relsz = 0; 30 Elf_Addr *where; 31 32 for (; dynp->d_tag != DT_NULL; dynp++) { 33 switch (dynp->d_tag) { 34 case DT_REL: 35 rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr); 36 break; 37 case DT_RELSZ: 38 relsz = dynp->d_un.d_val; 39 break; 40 } 41 } 42 rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz); 43 for (; rel < rellim; rel++) { 44 where = (Elf_Addr *)(relocbase + rel->r_offset); 45 *where += (Elf_Addr)relocbase; 46 } 47 } 48 49 /* 50 * It is possible for the compiler to emit relocations for unaligned data. 51 * We handle this situation with these inlines. 52 */ 53 #define RELOC_ALIGNED_P(x) \ 54 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) 55 56 static inline Elf_Addr 57 load_ptr(void *where) 58 { 59 Elf_Addr res; 60 61 memcpy(&res, where, sizeof(res)); 62 63 return (res); 64 } 65 66 static inline void 67 store_ptr(void *where, Elf_Addr val) 68 { 69 70 memcpy(where, &val, sizeof(val)); 71 } 72 73 int 74 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 75 { 76 const Elf_Rel *rel; 77 78 for (rel = obj->rel; rel < obj->rellim; rel++) { 79 Elf_Addr *where; 80 const Elf_Sym *def; 81 const Obj_Entry *defobj; 82 Elf_Addr tmp; 83 unsigned long symnum; 84 85 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 86 symnum = ELF_R_SYM(rel->r_info); 87 88 switch (ELF_R_TYPE(rel->r_info)) { 89 case R_TYPE(NONE): 90 break; 91 92 #if 1 /* XXX should not occur */ 93 case R_TYPE(PC24): { /* word32 S - P + A */ 94 Elf32_Sword addend; 95 96 /* 97 * Extract addend and sign-extend if needed. 98 */ 99 addend = *where; 100 if (addend & 0x00800000) 101 addend |= 0xff000000; 102 103 def = _rtld_find_symdef(symnum, obj, &defobj, false); 104 if (def == NULL) 105 return -1; 106 tmp = (Elf_Addr)obj->relocbase + def->st_value 107 - (Elf_Addr)where + (addend << 2); 108 if ((tmp & 0xfe000000) != 0xfe000000 && 109 (tmp & 0xfe000000) != 0) { 110 _rtld_error( 111 "%s: R_ARM_PC24 relocation @ %p to %s failed " 112 "(displacement %ld (%#lx) out of range)", 113 obj->path, where, 114 obj->strtab + obj->symtab[symnum].st_name, 115 (long) tmp, (long) tmp); 116 return -1; 117 } 118 tmp >>= 2; 119 *where = (*where & 0xff000000) | (tmp & 0x00ffffff); 120 rdbg(("PC24 %s in %s --> %p @ %p in %s", 121 obj->strtab + obj->symtab[symnum].st_name, 122 obj->path, (void *)*where, where, defobj->path)); 123 break; 124 } 125 #endif 126 127 case R_TYPE(ABS32): /* word32 B + S + A */ 128 case R_TYPE(GLOB_DAT): /* word32 B + S */ 129 def = _rtld_find_symdef(symnum, obj, &defobj, false); 130 if (def == NULL) 131 return -1; 132 if (__predict_true(RELOC_ALIGNED_P(where))) { 133 tmp = *where + (Elf_Addr)defobj->relocbase + 134 def->st_value; 135 /* Set the Thumb bit, if needed. */ 136 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) 137 tmp |= 1; 138 *where = tmp; 139 } else { 140 tmp = load_ptr(where) + 141 (Elf_Addr)defobj->relocbase + 142 def->st_value; 143 /* Set the Thumb bit, if needed. */ 144 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) 145 tmp |= 1; 146 store_ptr(where, tmp); 147 } 148 rdbg(("ABS32/GLOB_DAT %s in %s --> %p @ %p in %s", 149 obj->strtab + obj->symtab[symnum].st_name, 150 obj->path, (void *)tmp, where, defobj->path)); 151 break; 152 153 case R_TYPE(RELATIVE): /* word32 B + A */ 154 if (__predict_true(RELOC_ALIGNED_P(where))) { 155 tmp = *where + (Elf_Addr)obj->relocbase; 156 *where = tmp; 157 } else { 158 tmp = load_ptr(where) + 159 (Elf_Addr)obj->relocbase; 160 store_ptr(where, tmp); 161 } 162 rdbg(("RELATIVE in %s --> %p", obj->path, 163 (void *)tmp)); 164 break; 165 166 case R_TYPE(COPY): 167 /* 168 * These are deferred until all other relocations have 169 * been done. All we do here is make sure that the 170 * COPY relocation is not in a shared library. They 171 * are allowed only in executable files. 172 */ 173 if (obj->isdynamic) { 174 _rtld_error( 175 "%s: Unexpected R_COPY relocation in shared library", 176 obj->path); 177 return -1; 178 } 179 rdbg(("COPY (avoid in main)")); 180 break; 181 182 case R_TYPE(TLS_DTPOFF32): 183 def = _rtld_find_symdef(symnum, obj, &defobj, false); 184 if (def == NULL) 185 return -1; 186 187 tmp = (Elf_Addr)(def->st_value); 188 if (__predict_true(RELOC_ALIGNED_P(where))) 189 *where = tmp; 190 else 191 store_ptr(where, tmp); 192 193 rdbg(("TLS_DTPOFF32 %s in %s --> %p", 194 obj->strtab + obj->symtab[symnum].st_name, 195 obj->path, (void *)tmp)); 196 197 break; 198 case R_TYPE(TLS_DTPMOD32): 199 def = _rtld_find_symdef(symnum, obj, &defobj, false); 200 if (def == NULL) 201 return -1; 202 203 tmp = (Elf_Addr)(defobj->tlsindex); 204 if (__predict_true(RELOC_ALIGNED_P(where))) 205 *where = tmp; 206 else 207 store_ptr(where, tmp); 208 209 rdbg(("TLS_DTPMOD32 %s in %s --> %p", 210 obj->strtab + obj->symtab[symnum].st_name, 211 obj->path, (void *)tmp)); 212 213 break; 214 215 case R_TYPE(TLS_TPOFF32): 216 def = _rtld_find_symdef(symnum, obj, &defobj, false); 217 if (def == NULL) 218 return -1; 219 220 if (!defobj->tls_done && 221 _rtld_tls_offset_allocate(obj)) 222 return -1; 223 224 tmp = (Elf_Addr)def->st_value + defobj->tlsoffset + 225 sizeof(struct tls_tcb); 226 if (__predict_true(RELOC_ALIGNED_P(where))) 227 *where = tmp; 228 else 229 store_ptr(where, tmp); 230 rdbg(("TLS_TPOFF32 %s in %s --> %p", 231 obj->strtab + obj->symtab[symnum].st_name, 232 obj->path, (void *)tmp)); 233 break; 234 235 default: 236 rdbg(("sym = %lu, type = %lu, offset = %p, " 237 "contents = %p, symbol = %s", 238 symnum, (u_long)ELF_R_TYPE(rel->r_info), 239 (void *)rel->r_offset, (void *)load_ptr(where), 240 obj->strtab + obj->symtab[symnum].st_name)); 241 _rtld_error("%s: Unsupported relocation type %ld " 242 "in non-PLT relocations", 243 obj->path, (u_long) ELF_R_TYPE(rel->r_info)); 244 return -1; 245 } 246 } 247 return 0; 248 } 249 250 int 251 _rtld_relocate_plt_lazy(const Obj_Entry *obj) 252 { 253 const Elf_Rel *rel; 254 255 if (!obj->relocbase) 256 return 0; 257 258 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 259 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 260 261 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT)); 262 263 /* Just relocate the GOT slots pointing into the PLT */ 264 *where += (Elf_Addr)obj->relocbase; 265 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 266 } 267 268 return 0; 269 } 270 271 static int 272 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel, 273 Elf_Addr *tp) 274 { 275 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 276 Elf_Addr new_value; 277 const Elf_Sym *def; 278 const Obj_Entry *defobj; 279 unsigned long info = rel->r_info; 280 281 assert(ELF_R_TYPE(info) == R_TYPE(JUMP_SLOT)); 282 283 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 284 if (__predict_false(def == NULL)) 285 return -1; 286 if (__predict_false(def == &_rtld_sym_zero)) 287 return 0; 288 289 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 290 if (tp == NULL) 291 return 0; 292 new_value = _rtld_resolve_ifunc(defobj, def); 293 } else { 294 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 295 } 296 /* Set the Thumb bit, if needed. */ 297 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC) 298 new_value |= 1; 299 rdbg(("bind now/fixup in %s --> old=%p new=%p", 300 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 301 if (*where != new_value) 302 *where = new_value; 303 if (tp) 304 *tp = new_value; 305 306 return 0; 307 } 308 309 caddr_t 310 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 311 { 312 const Elf_Rel *rel = (const Elf_Rel *)((const uint8_t *)obj->pltrel + reloff); 313 Elf_Addr new_value = 0; /* XXX gcc */ 314 int err; 315 316 _rtld_shared_enter(); 317 err = _rtld_relocate_plt_object(obj, rel, &new_value); 318 if (err) 319 _rtld_die(); 320 _rtld_shared_exit(); 321 322 return (caddr_t)new_value; 323 } 324 int 325 _rtld_relocate_plt_objects(const Obj_Entry *obj) 326 { 327 const Elf_Rel *rel; 328 int err = 0; 329 330 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 331 err = _rtld_relocate_plt_object(obj, rel, NULL); 332 if (err) 333 break; 334 } 335 336 return err; 337 } 338
Indexes created Tue Sep 30 20:09:53 GMT 2025