mdreloc.c revision 1.36
1 /* $NetBSD: mdreloc.c,v 1.36 2014/08/25 20:40:52 joerg Exp $ */ 2 3 #include <sys/cdefs.h> 4 #ifndef lint 5 __RCSID("$NetBSD: mdreloc.c,v 1.36 2014/08/25 20:40:52 joerg Exp $"); 6 #endif /* not lint */ 7 8 #include <sys/types.h> 9 #include <sys/ucontext.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 if (rel == 0 || relsz == 0) 43 return; 44 rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz); 45 for (; rel < rellim; rel++) { 46 where = (Elf_Addr *)(relocbase + rel->r_offset); 47 *where += (Elf_Addr)relocbase; 48 } 49 } 50 51 int 52 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 53 { 54 const Elf_Rel *rel; 55 Elf_Addr target = 0; 56 57 for (rel = obj->rel; rel < obj->rellim; rel++) { 58 Elf_Addr *where; 59 const Elf_Sym *def; 60 const Obj_Entry *defobj; 61 Elf_Addr tmp; 62 unsigned long symnum; 63 64 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 65 symnum = ELF_R_SYM(rel->r_info); 66 67 switch (ELF_R_TYPE(rel->r_info)) { 68 case R_TYPE(NONE): 69 break; 70 71 #if 1 /* XXX should not occur */ 72 case R_TYPE(PC32): 73 def = _rtld_find_symdef(symnum, obj, &defobj, false); 74 if (def == NULL) 75 return -1; 76 target = (Elf_Addr)(defobj->relocbase + def->st_value); 77 78 *where += target - (Elf_Addr)where; 79 rdbg(("PC32 %s in %s --> %p in %s", 80 obj->strtab + obj->symtab[symnum].st_name, 81 obj->path, (void *)*where, defobj->path)); 82 break; 83 84 case R_TYPE(GOT32): 85 #endif 86 case R_TYPE(32): 87 case R_TYPE(GLOB_DAT): 88 def = _rtld_find_symdef(symnum, obj, &defobj, false); 89 if (def == NULL) 90 return -1; 91 target = (Elf_Addr)(defobj->relocbase + def->st_value); 92 93 tmp = target + *where; 94 if (*where != tmp) 95 *where = tmp; 96 rdbg(("32/GLOB_DAT %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(RELATIVE): 102 *where += (Elf_Addr)obj->relocbase; 103 rdbg(("RELATIVE in %s --> %p", obj->path, 104 (void *)*where)); 105 break; 106 107 case R_TYPE(COPY): 108 /* 109 * These are deferred until all other relocations have 110 * been done. All we do here is make sure that the 111 * COPY relocation is not in a shared library. They 112 * are allowed only in executable files. 113 */ 114 if (obj->isdynamic) { 115 _rtld_error( 116 "%s: Unexpected R_COPY relocation in shared library", 117 obj->path); 118 return -1; 119 } 120 rdbg(("COPY (avoid in main)")); 121 break; 122 123 case R_TYPE(TLS_TPOFF): 124 def = _rtld_find_symdef(symnum, obj, &defobj, false); 125 if (def == NULL) 126 return -1; 127 128 if (!defobj->tls_done && 129 _rtld_tls_offset_allocate(obj)) 130 return -1; 131 132 *where += (Elf_Addr)(def->st_value - defobj->tlsoffset); 133 134 rdbg(("TLS_TPOFF %s in %s --> %p", 135 obj->strtab + obj->symtab[symnum].st_name, 136 obj->path, (void *)*where)); 137 break; 138 139 case R_TYPE(TLS_TPOFF32): 140 def = _rtld_find_symdef(symnum, obj, &defobj, false); 141 if (def == NULL) 142 return -1; 143 144 if (!defobj->tls_done && 145 _rtld_tls_offset_allocate(obj)) 146 return -1; 147 148 *where += (Elf_Addr)(defobj->tlsoffset - def->st_value); 149 rdbg(("TLS_TPOFF32 %s in %s --> %p", 150 obj->strtab + obj->symtab[symnum].st_name, 151 obj->path, (void *)*where)); 152 break; 153 154 case R_TYPE(TLS_DTPMOD32): 155 def = _rtld_find_symdef(symnum, obj, &defobj, false); 156 if (def == NULL) 157 return -1; 158 159 *where = (Elf_Addr)(defobj->tlsindex); 160 161 rdbg(("TLS_DTPMOD32 %s in %s --> %p", 162 obj->strtab + obj->symtab[symnum].st_name, 163 obj->path, (void *)*where)); 164 break; 165 166 case R_TYPE(TLS_DTPOFF32): 167 def = _rtld_find_symdef(symnum, obj, &defobj, false); 168 if (def == NULL) 169 return -1; 170 171 *where = (Elf_Addr)(def->st_value); 172 173 rdbg(("TLS_DTPOFF32 %s in %s --> %p", 174 obj->strtab + obj->symtab[symnum].st_name, 175 obj->path, (void *)*where)); 176 177 break; 178 179 default: 180 rdbg(("sym = %lu, type = %lu, offset = %p, " 181 "contents = %p, symbol = %s", 182 symnum, (u_long)ELF_R_TYPE(rel->r_info), 183 (void *)rel->r_offset, (void *)*where, 184 obj->strtab + obj->symtab[symnum].st_name)); 185 _rtld_error("%s: Unsupported relocation type %ld " 186 "in non-PLT relocations", 187 obj->path, (u_long) ELF_R_TYPE(rel->r_info)); 188 return -1; 189 } 190 } 191 return 0; 192 } 193 194 int 195 _rtld_relocate_plt_lazy(const Obj_Entry *obj) 196 { 197 const Elf_Rel *rel; 198 199 if (!obj->relocbase) 200 return 0; 201 202 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 203 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 204 205 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JMP_SLOT)); 206 207 /* Just relocate the GOT slots pointing into the PLT */ 208 *where += (Elf_Addr)obj->relocbase; 209 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 210 } 211 212 return 0; 213 } 214 215 static inline int 216 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel, 217 Elf_Addr *tp) 218 { 219 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 220 Elf_Addr target; 221 const Elf_Sym *def; 222 const Obj_Entry *defobj; 223 unsigned long info = rel->r_info; 224 225 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 226 227 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 228 if (__predict_false(def == NULL)) 229 return -1; 230 if (__predict_false(def == &_rtld_sym_zero)) 231 return 0; 232 233 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 234 if (tp == NULL) 235 return 0; 236 target = _rtld_resolve_ifunc(defobj, def); 237 } else { 238 target = (Elf_Addr)(defobj->relocbase + def->st_value); 239 } 240 241 target = (Elf_Addr)(defobj->relocbase + def->st_value); 242 rdbg(("bind now/fixup in %s --> old=%p new=%p", 243 defobj->strtab + def->st_name, (void *)*where, 244 (void *)target)); 245 if (*where != target) 246 *where = target; 247 if (tp) 248 *tp = target; 249 return 0; 250 } 251 252 caddr_t 253 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 254 { 255 const Elf_Rel *rel = (const Elf_Rel *)((const uint8_t *)obj->pltrel 256 + reloff); 257 Elf_Addr new_value; 258 int err; 259 260 new_value = 0; /* XXX gcc */ 261 262 _rtld_shared_enter(); 263 err = _rtld_relocate_plt_object(obj, rel, &new_value); 264 if (err) 265 _rtld_die(); 266 _rtld_shared_exit(); 267 268 return (caddr_t)new_value; 269 } 270 271 int 272 _rtld_relocate_plt_objects(const Obj_Entry *obj) 273 { 274 const Elf_Rel *rel; 275 int err = 0; 276 277 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) { 278 err = _rtld_relocate_plt_object(obj, rel, NULL); 279 if (err) 280 break; 281 } 282 return err; 283 } 284 285 /* 286 * i386 specific GNU variant of __tls_get_addr using register based 287 * argument passing. 288 */ 289 #define DTV_MAX_INDEX(dtv) ((size_t)((dtv)[-1])) 290 291 __dso_public __attribute__((__regparm__(1))) void * 292 ___tls_get_addr(void *arg_) 293 { 294 size_t *arg = (size_t *)arg_; 295 void **dtv; 296 struct tls_tcb *tcb = __lwp_getprivate_fast(); 297 size_t idx = arg[0], offset = arg[1]; 298 299 dtv = tcb->tcb_dtv; 300 301 if (__predict_true(idx < DTV_MAX_INDEX(dtv) && dtv[idx] != NULL)) 302 return (uint8_t *)dtv[idx] + offset; 303 304 return _rtld_tls_get_addr(tcb, idx, offset); 305 } 306
Indexes created Tue Sep 30 11:09:46 GMT 2025