mdreloc.c revision 1.32
1 /* $NetBSD: mdreloc.c,v 1.32 2016/04/14 20:17:07 skrll Exp $ */ 2 3 #include <sys/cdefs.h> 4 #ifndef lint 5 __RCSID("$NetBSD: mdreloc.c,v 1.32 2016/04/14 20:17:07 skrll Exp $"); 6 #endif /* not lint */ 7 8 #include <sys/types.h> 9 #include <sys/tls.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 static inline int _rtld_relocate_plt_object(const Obj_Entry *, 18 const Elf_Rela *, Elf_Addr *); 19 20 void 21 _rtld_setup_pltgot(const Obj_Entry *obj) 22 { 23 obj->pltgot[1] = (Elf_Addr) obj; 24 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 25 } 26 27 void 28 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 29 { 30 const Elf_Rela *rela = 0, *relalim; 31 Elf_Addr relasz = 0; 32 Elf_Addr *where; 33 34 for (; dynp->d_tag != DT_NULL; dynp++) { 35 switch (dynp->d_tag) { 36 case DT_RELA: 37 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); 38 break; 39 case DT_RELASZ: 40 relasz = dynp->d_un.d_val; 41 break; 42 } 43 } 44 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); 45 for (; rela < relalim; rela++) { 46 where = (Elf_Addr *)(relocbase + rela->r_offset); 47 *where = (Elf_Addr)(relocbase + rela->r_addend); 48 } 49 } 50 51 int 52 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 53 { 54 const Elf_Rela *rela; 55 56 for (rela = obj->rela; rela < obj->relalim; rela++) { 57 Elf_Addr *where; 58 const Elf_Sym *def; 59 const Obj_Entry *defobj; 60 Elf_Addr tmp; 61 unsigned long symnum; 62 63 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 64 symnum = ELF_R_SYM(rela->r_info); 65 66 switch (ELF_R_TYPE(rela->r_info)) { 67 case R_TYPE(NONE): 68 break; 69 70 #if 1 /* XXX should not occur */ 71 case R_TYPE(GOT32): 72 def = _rtld_find_symdef(symnum, obj, &defobj, false); 73 if (def == NULL) 74 return -1; 75 76 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 77 rela->r_addend); 78 if (*where != tmp) 79 *where = tmp; 80 rdbg(("GOT32 %s in %s --> %p in %s", 81 obj->strtab + obj->symtab[symnum].st_name, 82 obj->path, (void *)*where, defobj->path)); 83 break; 84 85 case R_TYPE(REL32): 86 def = _rtld_find_symdef(symnum, obj, &defobj, false); 87 if (def == NULL) 88 return -1; 89 90 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 91 rela->r_addend) - (Elf_Addr)where; 92 if (*where != tmp) 93 *where = tmp; 94 rdbg(("PC32 %s in %s --> %p in %s", 95 obj->strtab + obj->symtab[symnum].st_name, 96 obj->path, (void *)*where, defobj->path)); 97 break; 98 #endif 99 100 case R_TYPE(DIR32): 101 def = _rtld_find_symdef(symnum, obj, &defobj, false); 102 if (def == NULL) 103 return -1; 104 105 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 106 rela->r_addend); 107 if (*where != tmp) 108 *where = tmp; 109 rdbg(("32 %s in %s --> %p in %s", 110 obj->strtab + obj->symtab[symnum].st_name, 111 obj->path, (void *)*where, defobj->path)); 112 break; 113 114 case R_TYPE(GLOB_DAT): 115 def = _rtld_find_symdef(symnum, obj, &defobj, false); 116 if (def == NULL) 117 return -1; 118 119 tmp = (Elf_Addr)(defobj->relocbase + def->st_value) + 120 rela->r_addend; 121 if (*where != tmp) 122 *where = tmp; 123 rdbg(("GLOB_DAT %s in %s --> %p in %s", 124 obj->strtab + obj->symtab[symnum].st_name, 125 obj->path, (void *)*where, defobj->path)); 126 break; 127 128 case R_TYPE(RELATIVE): 129 if (rela->r_addend) 130 *where = (Elf_Addr)obj->relocbase + rela->r_addend; 131 else 132 *where += (Elf_Addr)obj->relocbase; 133 rdbg(("RELATIVE in %s --> %p", obj->path, 134 (void *)*where)); 135 break; 136 137 case R_TYPE(COPY): 138 /* 139 * These are deferred until all other relocations have 140 * been done. All we do here is make sure that the 141 * COPY relocation is not in a shared library. They 142 * are allowed only in executable files. 143 */ 144 if (obj->isdynamic) { 145 _rtld_error( 146 "%s: Unexpected R_COPY relocation in shared library", 147 obj->path); 148 return -1; 149 } 150 rdbg(("COPY (avoid in main)")); 151 break; 152 153 case R_TYPE(TLS_DTPOFF32): 154 def = _rtld_find_symdef(symnum, obj, &defobj, false); 155 if (def == NULL) 156 return -1; 157 158 *where = (Elf_Addr)(def->st_value); 159 160 rdbg(("TLS_DTPOFF32 %s in %s --> %p", 161 obj->strtab + obj->symtab[symnum].st_name, 162 obj->path, (void *)*where)); 163 164 break; 165 case R_TYPE(TLS_DTPMOD32): 166 def = _rtld_find_symdef(symnum, obj, &defobj, false); 167 if (def == NULL) 168 return -1; 169 170 *where = (Elf_Addr)(defobj->tlsindex); 171 172 rdbg(("TLS_DTPMOD32 %s in %s --> %p", 173 obj->strtab + obj->symtab[symnum].st_name, 174 obj->path, (void *)*where)); 175 176 break; 177 178 case R_TYPE(TLS_TPOFF32): 179 def = _rtld_find_symdef(symnum, obj, &defobj, false); 180 if (def == NULL) 181 return -1; 182 183 if (!defobj->tls_done && 184 _rtld_tls_offset_allocate(obj)) 185 return -1; 186 187 *where = (Elf_Addr)def->st_value + 188 rela->r_addend + defobj->tlsoffset + 189 sizeof(struct tls_tcb); 190 191 rdbg(("TLS_TPOFF32 %s in %s --> %p", 192 obj->strtab + obj->symtab[symnum].st_name, 193 obj->path, (void *)*where)); 194 break; 195 196 default: 197 rdbg(("sym = %lu, type = %lu, offset = %p, " 198 "addend = %p, contents = %p, symbol = %s", 199 symnum, (u_long)ELF_R_TYPE(rela->r_info), 200 (void *)rela->r_offset, (void *)rela->r_addend, 201 (void *)*where, 202 obj->strtab + obj->symtab[symnum].st_name)); 203 _rtld_error("%s: Unsupported relocation type %ld " 204 "in non-PLT relocations", 205 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 206 return -1; 207 } 208 } 209 return 0; 210 } 211 212 int 213 _rtld_relocate_plt_lazy(const Obj_Entry *obj) 214 { 215 const Elf_Rela *rela; 216 217 if (!obj->relocbase) 218 return 0; 219 220 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) { 221 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 222 223 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 224 225 /* Just relocate the GOT slots pointing into the PLT */ 226 *where += (Elf_Addr)obj->relocbase; 227 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 228 } 229 230 return 0; 231 } 232 233 caddr_t 234 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 235 { 236 const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff); 237 Elf_Addr new_value; 238 int err; 239 240 new_value = 0; /* XXX gcc */ 241 242 _rtld_shared_enter(); 243 err = _rtld_relocate_plt_object(obj, rela, &new_value); 244 if (err) 245 _rtld_die(); 246 _rtld_shared_exit(); 247 248 return (caddr_t)new_value; 249 } 250 251 int 252 _rtld_relocate_plt_objects(const Obj_Entry *obj) 253 { 254 const Elf_Rela *rela = obj->pltrela; 255 256 for (; rela < obj->pltrelalim; rela++) 257 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0) 258 return -1; 259 260 return 0; 261 } 262 263 static inline int 264 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp) 265 { 266 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 267 Elf_Addr new_value; 268 const Elf_Sym *def; 269 const Obj_Entry *defobj; 270 unsigned long info = rela->r_info; 271 272 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 273 274 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 275 if (__predict_false(def == NULL)) 276 return -1; 277 if (__predict_false(def == &_rtld_sym_zero)) 278 return 0; 279 280 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 281 if (tp == NULL) 282 return 0; 283 new_value = _rtld_resolve_ifunc(defobj, def); 284 } else { 285 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 286 } 287 rdbg(("bind now/fixup in %s --> old=%p new=%p", 288 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 289 if (*where != new_value) 290 *where = new_value; 291 292 if (tp) 293 *tp = new_value; 294 295 return 0; 296 } 297
Indexes created Tue Oct 21 12:09:54 GMT 2025