mdreloc.c revision 1.5
1 /* $NetBSD: mdreloc.c,v 1.5 2024/08/03 21:59:58 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2014 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Matt Thomas of 3am Software Foundry. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #ifndef lint 34 __RCSID("$NetBSD: mdreloc.c,v 1.5 2024/08/03 21:59:58 riastradh Exp $"); 35 #endif /* not lint */ 36 37 #include <stdarg.h> 38 #include <stdio.h> 39 #include <stdlib.h> 40 #include <string.h> 41 #include <sys/types.h> 42 #include <machine/cpu.h> 43 44 #include "debug.h" 45 #include "rtld.h" 46 47 void _rtld_bind_start(void); 48 Elf_Addr _rtld_bind(const Obj_Entry *, Elf_Word); 49 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 50 static int _rtld_relocate_plt_object(const Obj_Entry *, 51 const Elf_Rela *, int, Elf_Addr *); 52 53 /* 54 * The OR1k PLT format is simple. 55 */ 56 57 void 58 _rtld_setup_pltgot(const Obj_Entry *obj) 59 { 60 obj->pltgot[1] = (Elf_Addr) obj; 61 obj->pltgot[2] = (Elf_Addr) _rtld_bind_start; 62 63 dbg(("obj %s plt pltgot=%p start=%p obj=%p", 64 obj->path, obj->pltgot, 65 (void *) obj->pltgot[1], (void *) obj->pltgot[2])); 66 } 67 68 void 69 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 70 { 71 const Elf_Rela *rela = 0, *relalim; 72 Elf_Addr relasz = 0; 73 Elf_Addr *where; 74 75 for (; dynp->d_tag != DT_NULL; dynp++) { 76 switch (dynp->d_tag) { 77 case DT_RELA: 78 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); 79 break; 80 case DT_RELASZ: 81 relasz = dynp->d_un.d_val; 82 break; 83 } 84 } 85 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); 86 for (; rela < relalim; rela++) { 87 where = (Elf_Addr *)(relocbase + rela->r_offset); 88 *where = (Elf_Addr)(relocbase + rela->r_addend); 89 } 90 } 91 92 int 93 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 94 { 95 const Elf_Rela *rela; 96 const Elf_Sym *def = NULL; 97 const Obj_Entry *defobj = NULL; 98 unsigned long last_symnum = ULONG_MAX; 99 100 for (rela = obj->rela; rela < obj->relalim; rela++) { 101 Elf_Addr *where; 102 Elf_Addr tmp; 103 unsigned long symnum; 104 105 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 106 107 switch (ELF_R_TYPE(rela->r_info)) { 108 case R_TYPE(32): /* <address> S + A */ 109 case R_TYPE(GLOB_DAT): /* <address> S + A */ 110 case R_TYPE(TLS_DTPMOD): 111 case R_TYPE(TLS_DTPOFF): 112 case R_TYPE(TLS_TPOFF): 113 symnum = ELF_R_SYM(rela->r_info); 114 if (last_symnum != symnum) { 115 last_symnum = symnum; 116 def = _rtld_find_symdef(symnum, obj, &defobj, 117 false); 118 if (def == NULL) 119 return -1; 120 } 121 break; 122 default: 123 break; 124 } 125 126 switch (ELF_R_TYPE(rela->r_info)) { 127 #if 1 /* XXX Should not be necessary. */ 128 case R_TYPE(JMP_SLOT): 129 #endif 130 case R_TYPE(NONE): 131 break; 132 133 case R_TYPE(32): /* <address> S + A */ 134 case R_TYPE(GLOB_DAT): /* <address> S + A */ 135 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 136 rela->r_addend); 137 if (*where != tmp) 138 *where = tmp; 139 rdbg(("32/GLOB_DAT %s in %s --> %p in %s", 140 obj->strtab + obj->symtab[symnum].st_name, 141 obj->path, (void *)*where, defobj->path)); 142 break; 143 144 case R_TYPE(RELATIVE): /* <address> B + A */ 145 *where = (Elf_Addr)(obj->relocbase + rela->r_addend); 146 rdbg(("RELATIVE in %s --> %p", obj->path, 147 (void *)*where)); 148 break; 149 150 case R_TYPE(COPY): 151 /* 152 * These are deferred until all other relocations have 153 * been done. All we do here is make sure that the 154 * COPY relocation is not in a shared library. They 155 * are allowed only in executable files. 156 */ 157 if (obj->isdynamic) { 158 _rtld_error( 159 "%s: Unexpected R_COPY relocation in shared library", 160 obj->path); 161 return -1; 162 } 163 rdbg(("COPY (avoid in main)")); 164 break; 165 166 case R_TYPE(TLS_DTPMOD): 167 *where = (Elf_Addr)defobj->tlsindex; 168 rdbg(("DTPMOD32 %s in %s --> %p in %s", 169 obj->strtab + obj->symtab[symnum].st_name, 170 obj->path, (void *)*where, defobj->path)); 171 break; 172 173 case R_TYPE(TLS_DTPOFF): 174 *where = (Elf_Addr)(def->st_value + rela->r_addend 175 - TLS_DTV_OFFSET); 176 rdbg(("DTPOFF %s in %s --> %p in %s", 177 obj->strtab + obj->symtab[symnum].st_name, 178 obj->path, (void *)*where, defobj->path)); 179 break; 180 181 case R_TYPE(TLS_TPOFF): 182 if (!defobj->tls_static && 183 _rtld_tls_offset_allocate(__UNCONST(defobj))) 184 return -1; 185 186 *where = (Elf_Addr)(def->st_value + rela->r_addend 187 + defobj->tlsoffset - TLS_TP_OFFSET); 188 rdbg(("TPREL %s in %s --> %p in %s", 189 obj->strtab + obj->symtab[symnum].st_name, 190 obj->path, (void *)*where, defobj->path)); 191 break; 192 193 default: 194 rdbg(("sym = %lu, type = %lu, offset = %p, " 195 "addend = %p, contents = %p, symbol = %s", 196 (u_long)ELF_R_SYM(rela->r_info), 197 (u_long)ELF_R_TYPE(rela->r_info), 198 (void *)rela->r_offset, (void *)rela->r_addend, 199 (void *)*where, 200 obj->strtab + obj->symtab[symnum].st_name)); 201 _rtld_error("%s: Unsupported relocation type %ld " 202 "in non-PLT relocations", 203 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 204 return -1; 205 } 206 } 207 return 0; 208 } 209 210 int 211 _rtld_relocate_plt_lazy(Obj_Entry *obj) 212 { 213 const Elf_Rela *rela; 214 int reloff; 215 216 for (rela = obj->pltrela, reloff = 0; 217 rela < obj->pltrelalim; 218 rela++, reloff++) { 219 Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset); 220 221 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 222 223 /* 224 * For now, simply treat then as relative. 225 */ 226 *where += (Elf_Addr)obj->relocbase; 227 } 228 229 return 0; 230 } 231 232 static int 233 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, int reloff, Elf_Addr *tp) 234 { 235 Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset); 236 Elf_Addr value; 237 const Elf_Sym *def; 238 const Obj_Entry *defobj; 239 unsigned long info = rela->r_info; 240 241 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 242 243 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 244 if (__predict_false(def == NULL)) 245 return -1; 246 if (__predict_false(def == &_rtld_sym_zero)) 247 return 0; 248 249 value = (Elf_Addr)(defobj->relocbase + def->st_value); 250 rdbg(("bind now/fixup in %s --> new=%p", 251 defobj->strtab + def->st_name, (void *)value)); 252 253 /* 254 * Simply replace the entry in GOT with the 255 * address of the routine. 256 */ 257 assert(where >= (Elf_Word *)obj->pltgot); 258 assert(where < (Elf_Word *)obj->pltgot + (obj->pltrelalim - obj->pltrela)); 259 *where = value; 260 261 if (tp) 262 *tp = value; 263 return 0; 264 } 265 266 Elf_Addr 267 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 268 { 269 const Elf_Rela *rela = obj->pltrela + reloff; 270 Elf_Addr new_value; 271 int err; 272 273 new_value = 0; /* XXX gcc */ 274 275 _rtld_shared_enter(); 276 err = _rtld_relocate_plt_object(obj, rela, reloff, &new_value); 277 if (err) 278 _rtld_die(); 279 _rtld_shared_exit(); 280 281 return new_value; 282 } 283 284 int 285 _rtld_relocate_plt_objects(const Obj_Entry *obj) 286 { 287 const Elf_Rela *rela; 288 int reloff; 289 290 for (rela = obj->pltrela, reloff = 0; rela < obj->pltrelalim; rela++, reloff++) { 291 if (_rtld_relocate_plt_object(obj, rela, reloff, NULL) < 0) 292 return -1; 293 } 294 return 0; 295 } 296
Indexes created Thu Oct 02 14:10:14 GMT 2025