mdreloc.c revision 1.33
1 /* $NetBSD: mdreloc.c,v 1.33 2017/06/19 11:57:02 joerg Exp $ */ 2 3 #include <sys/cdefs.h> 4 #ifndef lint 5 __RCSID("$NetBSD: mdreloc.c,v 1.33 2017/06/19 11:57:02 joerg 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 65 switch (ELF_R_TYPE(rela->r_info)) { 66 case R_TYPE(GOT32): 67 case R_TYPE(REL32): 68 case R_TYPE(DIR32): 69 case R_TYPE(GLOB_DAT): 70 case R_TYPE(TLS_DTPOFF32): 71 case R_TYPE(TLS_DTPMOD32): 72 case R_TYPE(TLS_TPOFF32): 73 symnum = ELF_R_SYM(rela->r_info); 74 if (last_symnum != symnum) { 75 last_symnum = symnum; 76 def = _rtld_find_symdef(symnum, obj, &defobj, 77 false); 78 if (def == NULL) 79 return -1; 80 } 81 break; 82 default: 83 break; 84 } 85 86 switch (ELF_R_TYPE(rela->r_info)) { 87 case R_TYPE(NONE): 88 break; 89 90 #if 1 /* XXX should not occur */ 91 case R_TYPE(GOT32): 92 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 93 rela->r_addend); 94 if (*where != tmp) 95 *where = tmp; 96 rdbg(("GOT32 %s in %s --> %p in %s", 97 obj->strtab + obj->symtab[symnum].st_name, 98 obj->path, (void *)*where, defobj->path)); 99 break; 100 101 case R_TYPE(REL32): 102 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 103 rela->r_addend) - (Elf_Addr)where; 104 if (*where != tmp) 105 *where = tmp; 106 rdbg(("PC32 %s in %s --> %p in %s", 107 obj->strtab + obj->symtab[symnum].st_name, 108 obj->path, (void *)*where, defobj->path)); 109 break; 110 #endif 111 112 case R_TYPE(DIR32): 113 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 114 rela->r_addend); 115 if (*where != tmp) 116 *where = tmp; 117 rdbg(("32 %s in %s --> %p in %s", 118 obj->strtab + obj->symtab[symnum].st_name, 119 obj->path, (void *)*where, defobj->path)); 120 break; 121 122 case R_TYPE(GLOB_DAT): 123 tmp = (Elf_Addr)(defobj->relocbase + def->st_value) + 124 rela->r_addend; 125 if (*where != tmp) 126 *where = tmp; 127 rdbg(("GLOB_DAT %s in %s --> %p in %s", 128 obj->strtab + obj->symtab[symnum].st_name, 129 obj->path, (void *)*where, defobj->path)); 130 break; 131 132 case R_TYPE(RELATIVE): 133 if (rela->r_addend) 134 *where = (Elf_Addr)obj->relocbase + rela->r_addend; 135 else 136 *where += (Elf_Addr)obj->relocbase; 137 rdbg(("RELATIVE in %s --> %p", obj->path, 138 (void *)*where)); 139 break; 140 141 case R_TYPE(COPY): 142 /* 143 * These are deferred until all other relocations have 144 * been done. All we do here is make sure that the 145 * COPY relocation is not in a shared library. They 146 * are allowed only in executable files. 147 */ 148 if (obj->isdynamic) { 149 _rtld_error( 150 "%s: Unexpected R_COPY relocation in shared library", 151 obj->path); 152 return -1; 153 } 154 rdbg(("COPY (avoid in main)")); 155 break; 156 157 case R_TYPE(TLS_DTPOFF32): 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 *where = (Elf_Addr)(defobj->tlsindex); 167 168 rdbg(("TLS_DTPMOD32 %s in %s --> %p", 169 obj->strtab + obj->symtab[symnum].st_name, 170 obj->path, (void *)*where)); 171 172 break; 173 174 case R_TYPE(TLS_TPOFF32): 175 if (!defobj->tls_done && 176 _rtld_tls_offset_allocate(obj)) 177 return -1; 178 179 *where = (Elf_Addr)def->st_value + 180 rela->r_addend + defobj->tlsoffset + 181 sizeof(struct tls_tcb); 182 183 rdbg(("TLS_TPOFF32 %s in %s --> %p", 184 obj->strtab + obj->symtab[symnum].st_name, 185 obj->path, (void *)*where)); 186 break; 187 188 default: 189 rdbg(("sym = %lu, type = %lu, offset = %p, " 190 "addend = %p, contents = %p, symbol = %s", 191 (u_long)ELF_R_SYM(rela->r_info), 192 (u_long)ELF_R_TYPE(rela->r_info), 193 (void *)rela->r_offset, (void *)rela->r_addend, 194 (void *)*where, 195 obj->strtab + obj->symtab[symnum].st_name)); 196 _rtld_error("%s: Unsupported relocation type %ld " 197 "in non-PLT relocations", 198 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 199 return -1; 200 } 201 } 202 return 0; 203 } 204 205 int 206 _rtld_relocate_plt_lazy(const Obj_Entry *obj) 207 { 208 const Elf_Rela *rela; 209 210 if (!obj->relocbase) 211 return 0; 212 213 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) { 214 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 215 216 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 217 218 /* Just relocate the GOT slots pointing into the PLT */ 219 *where += (Elf_Addr)obj->relocbase; 220 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 221 } 222 223 return 0; 224 } 225 226 caddr_t 227 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 228 { 229 const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff); 230 Elf_Addr new_value; 231 int err; 232 233 new_value = 0; /* XXX gcc */ 234 235 _rtld_shared_enter(); 236 err = _rtld_relocate_plt_object(obj, rela, &new_value); 237 if (err) 238 _rtld_die(); 239 _rtld_shared_exit(); 240 241 return (caddr_t)new_value; 242 } 243 244 int 245 _rtld_relocate_plt_objects(const Obj_Entry *obj) 246 { 247 const Elf_Rela *rela = obj->pltrela; 248 249 for (; rela < obj->pltrelalim; rela++) 250 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0) 251 return -1; 252 253 return 0; 254 } 255 256 static inline int 257 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp) 258 { 259 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 260 Elf_Addr new_value; 261 const Elf_Sym *def; 262 const Obj_Entry *defobj; 263 unsigned long info = rela->r_info; 264 265 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 266 267 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 268 if (__predict_false(def == NULL)) 269 return -1; 270 if (__predict_false(def == &_rtld_sym_zero)) 271 return 0; 272 273 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 274 if (tp == NULL) 275 return 0; 276 new_value = _rtld_resolve_ifunc(defobj, def); 277 } else { 278 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 279 } 280 rdbg(("bind now/fixup in %s --> old=%p new=%p", 281 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 282 if (*where != new_value) 283 *where = new_value; 284 285 if (tp) 286 *tp = new_value; 287 288 return 0; 289 } 290
Indexes created Tue Sep 30 20:09:53 GMT 2025