mdreloc.c revision 1.37
1 /* $NetBSD: mdreloc.c,v 1.37 2024/07/23 09:27:00 uwe Exp $ */ 2 3 #include <sys/cdefs.h> 4 #ifndef lint 5 __RCSID("$NetBSD: mdreloc.c,v 1.37 2024/07/23 09:27:00 uwe Exp $"); 6 #endif /* not lint */ 7 8 /* 9 * SuperH ELF relocations. 10 * 11 * Reference: 12 * 13 * [RM0197] SH-4 generic and C specific application binary interface 14 * https://www.st.com/resource/en/reference_manual/rm0197-sh4-generic-and-c-specific-application-binary-interface-stmicroelectronics.pdf 15 */ 16 17 #include <sys/types.h> 18 #include <sys/tls.h> 19 20 #include "debug.h" 21 #include "rtld.h" 22 23 void _rtld_bind_start(void); 24 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 25 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 26 static inline int _rtld_relocate_plt_object(const Obj_Entry *, 27 const Elf_Rela *, Elf_Addr *); 28 29 void 30 _rtld_setup_pltgot(const Obj_Entry *obj) 31 { 32 obj->pltgot[1] = (Elf_Addr) obj; 33 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 34 } 35 36 void 37 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 38 { 39 const Elf_Rela *rela = 0, *relalim; 40 Elf_Addr relasz = 0; 41 Elf_Addr *where; 42 43 for (; dynp->d_tag != DT_NULL; dynp++) { 44 switch (dynp->d_tag) { 45 case DT_RELA: 46 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); 47 break; 48 case DT_RELASZ: 49 relasz = dynp->d_un.d_val; 50 break; 51 } 52 } 53 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); 54 for (; rela < relalim; rela++) { 55 where = (Elf_Addr *)(relocbase + rela->r_offset); 56 *where = (Elf_Addr)(relocbase + rela->r_addend); 57 } 58 } 59 60 int 61 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 62 { 63 const Elf_Rela *rela; 64 const Elf_Sym *def = NULL; 65 const Obj_Entry *defobj = NULL; 66 unsigned long last_symnum = ULONG_MAX; 67 68 for (rela = obj->rela; rela < obj->relalim; rela++) { 69 Elf_Addr *where; 70 Elf_Addr tmp; 71 unsigned long symnum; 72 73 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 74 75 switch (ELF_R_TYPE(rela->r_info)) { 76 case R_TYPE(GOT32): 77 case R_TYPE(REL32): 78 case R_TYPE(DIR32): 79 case R_TYPE(GLOB_DAT): 80 case R_TYPE(TLS_DTPOFF32): 81 case R_TYPE(TLS_DTPMOD32): 82 case R_TYPE(TLS_TPOFF32): 83 symnum = ELF_R_SYM(rela->r_info); 84 if (last_symnum != symnum) { 85 last_symnum = symnum; 86 def = _rtld_find_symdef(symnum, obj, &defobj, 87 false); 88 if (def == NULL) 89 return -1; 90 } 91 break; 92 default: 93 break; 94 } 95 96 switch (ELF_R_TYPE(rela->r_info)) { 97 case R_TYPE(NONE): 98 break; 99 100 #if 1 /* XXX should not occur */ 101 case R_TYPE(GOT32): 102 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 103 rela->r_addend); 104 if (*where != tmp) 105 *where = tmp; 106 rdbg(("GOT32 %s in %s --> %p in %s", 107 obj->strtab + obj->symtab[symnum].st_name, 108 obj->path, (void *)*where, defobj->path)); 109 break; 110 111 case R_TYPE(REL32): 112 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 113 rela->r_addend) - (Elf_Addr)where; 114 if (*where != tmp) 115 *where = tmp; 116 rdbg(("PC32 %s in %s --> %p in %s", 117 obj->strtab + obj->symtab[symnum].st_name, 118 obj->path, (void *)*where, defobj->path)); 119 break; 120 #endif 121 122 case R_TYPE(DIR32): 123 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 124 rela->r_addend); 125 if (*where != tmp) 126 *where = tmp; 127 rdbg(("32 %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(GLOB_DAT): 133 tmp = (Elf_Addr)(defobj->relocbase + def->st_value) + 134 rela->r_addend; 135 if (*where != tmp) 136 *where = tmp; 137 rdbg(("GLOB_DAT %s in %s --> %p in %s", 138 obj->strtab + obj->symtab[symnum].st_name, 139 obj->path, (void *)*where, defobj->path)); 140 break; 141 142 case R_TYPE(RELATIVE): 143 if (rela->r_addend) 144 *where = (Elf_Addr)obj->relocbase + rela->r_addend; 145 else 146 *where += (Elf_Addr)obj->relocbase; 147 rdbg(("RELATIVE in %s --> %p", obj->path, 148 (void *)*where)); 149 break; 150 151 case R_TYPE(COPY): 152 /* 153 * These are deferred until all other relocations have 154 * been done. All we do here is make sure that the 155 * COPY relocation is not in a shared library. They 156 * are allowed only in executable files. 157 */ 158 if (obj->isdynamic) { 159 _rtld_error( 160 "%s: Unexpected R_COPY relocation in shared library", 161 obj->path); 162 return -1; 163 } 164 rdbg(("COPY (avoid in main)")); 165 break; 166 167 case R_TYPE(TLS_DTPOFF32): 168 *where = (Elf_Addr)(def->st_value); 169 170 rdbg(("TLS_DTPOFF32 %s in %s --> %p", 171 obj->strtab + obj->symtab[symnum].st_name, 172 obj->path, (void *)*where)); 173 174 break; 175 case R_TYPE(TLS_DTPMOD32): 176 *where = (Elf_Addr)(defobj->tlsindex); 177 178 rdbg(("TLS_DTPMOD32 %s in %s --> %p", 179 obj->strtab + obj->symtab[symnum].st_name, 180 obj->path, (void *)*where)); 181 182 break; 183 184 case R_TYPE(TLS_TPOFF32): 185 if (!defobj->tls_static && 186 _rtld_tls_offset_allocate(__UNCONST(defobj))) 187 return -1; 188 189 *where = (Elf_Addr)def->st_value + 190 rela->r_addend + defobj->tlsoffset + 191 sizeof(struct tls_tcb); 192 193 rdbg(("TLS_TPOFF32 %s in %s --> %p", 194 obj->strtab + obj->symtab[symnum].st_name, 195 obj->path, (void *)*where)); 196 break; 197 198 default: 199 rdbg(("sym = %lu, type = %lu, offset = %p, " 200 "addend = %p, contents = %p, symbol = %s", 201 (u_long)ELF_R_SYM(rela->r_info), 202 (u_long)ELF_R_TYPE(rela->r_info), 203 (void *)rela->r_offset, (void *)rela->r_addend, 204 (void *)*where, 205 obj->strtab + obj->symtab[symnum].st_name)); 206 _rtld_error("%s: Unsupported relocation type %ld " 207 "in non-PLT relocations", 208 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 209 return -1; 210 } 211 } 212 return 0; 213 } 214 215 int 216 _rtld_relocate_plt_lazy(Obj_Entry *obj) 217 { 218 const Elf_Rela *rela; 219 220 if (!obj->relocbase) 221 return 0; 222 223 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) { 224 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 225 226 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 227 228 /* Just relocate the GOT slots pointing into the PLT */ 229 *where += (Elf_Addr)obj->relocbase; 230 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where)); 231 } 232 233 return 0; 234 } 235 236 caddr_t 237 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 238 { 239 const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff); 240 Elf_Addr new_value; 241 int err; 242 243 new_value = 0; /* XXX gcc */ 244 245 _rtld_shared_enter(); 246 err = _rtld_relocate_plt_object(obj, rela, &new_value); 247 if (err) 248 _rtld_die(); 249 _rtld_shared_exit(); 250 251 return (caddr_t)new_value; 252 } 253 254 int 255 _rtld_relocate_plt_objects(const Obj_Entry *obj) 256 { 257 const Elf_Rela *rela = obj->pltrela; 258 259 for (; rela < obj->pltrelalim; rela++) 260 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0) 261 return -1; 262 263 return 0; 264 } 265 266 static inline int 267 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp) 268 { 269 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 270 Elf_Addr new_value; 271 const Elf_Sym *def; 272 const Obj_Entry *defobj; 273 unsigned long info = rela->r_info; 274 275 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 276 277 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 278 if (__predict_false(def == NULL)) 279 return -1; 280 if (__predict_false(def == &_rtld_sym_zero)) 281 return 0; 282 283 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 284 if (tp == NULL) 285 return 0; 286 new_value = _rtld_resolve_ifunc(defobj, def); 287 } else { 288 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 289 } 290 rdbg(("bind now/fixup in %s --> old=%p new=%p", 291 defobj->strtab + def->st_name, (void *)*where, (void *)new_value)); 292 if (*where != new_value) 293 *where = new_value; 294 295 if (tp) 296 *tp = new_value; 297 298 return 0; 299 } 300
Indexes created Mon Sep 29 21:09:56 GMT 2025