mips_reloc.c revision 1.40
1 /* $NetBSD: mips_reloc.c,v 1.40 2003/07/26 15:04:41 mrg Exp $ */ 2 3 /* 4 * Copyright 1997 Michael L. Hitch <mhitch (at) montana.edu> 5 * Portions copyright 2002 Charles M. Hannum <root (at) ihack.net> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include <sys/types.h> 32 #include <sys/stat.h> 33 34 #include <stdlib.h> 35 #include <string.h> 36 37 #include "debug.h" 38 #include "rtld.h" 39 40 #define SUPPORT_OLD_BROKEN_LD 41 42 void _rtld_bind_start(void); 43 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 44 caddr_t _rtld_bind(Elf_Word, Elf_Addr, Elf_Addr, Elf_Addr); 45 46 void 47 _rtld_setup_pltgot(const Obj_Entry *obj) 48 { 49 obj->pltgot[0] = (Elf_Addr) &_rtld_bind_start; 50 /* XXX only if obj->pltgot[1] & 0x80000000 ?? */ 51 obj->pltgot[1] |= (Elf_Addr) obj; 52 } 53 54 void 55 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 56 { 57 const Elf_Rel *rel = 0, *rellim; 58 Elf_Addr relsz = 0; 59 Elf_Addr *where; 60 const Elf_Sym *symtab, *sym; 61 Elf_Addr *got; 62 Elf_Word local_gotno, symtabno, gotsym; 63 int i; 64 65 for (; dynp->d_tag != DT_NULL; dynp++) { 66 switch (dynp->d_tag) { 67 case DT_REL: 68 rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr); 69 break; 70 case DT_RELSZ: 71 relsz = dynp->d_un.d_val; 72 break; 73 case DT_SYMTAB: 74 symtab = (const Elf_Sym *)(relocbase + dynp->d_un.d_ptr); 75 break; 76 case DT_PLTGOT: 77 got = (Elf_Addr *)(relocbase + dynp->d_un.d_ptr); 78 break; 79 case DT_MIPS_LOCAL_GOTNO: 80 local_gotno = dynp->d_un.d_val; 81 break; 82 case DT_MIPS_SYMTABNO: 83 symtabno = dynp->d_un.d_val; 84 break; 85 case DT_MIPS_GOTSYM: 86 gotsym = dynp->d_un.d_val; 87 break; 88 } 89 } 90 91 i = (got[1] & 0x80000000) ? 2 : 1; 92 /* Relocate the local GOT entries */ 93 got += i; 94 for (; i < local_gotno; i++) 95 *got++ += relocbase; 96 sym = symtab + gotsym; 97 /* Now do the global GOT entries */ 98 for (i = gotsym; i < symtabno; i++) { 99 *got = sym->st_value + relocbase; 100 ++sym; 101 ++got; 102 } 103 104 rellim = (const Elf_Rel *)((caddr_t)rel + relsz); 105 for (; rel < rellim; rel++) { 106 where = (Elf_Addr *)(relocbase + rel->r_offset); 107 108 switch (ELF_R_TYPE(rel->r_info)) { 109 case R_TYPE(NONE): 110 break; 111 112 case R_TYPE(REL32): 113 assert(ELF_R_SYM(rel->r_info) < gotsym); 114 sym = symtab + ELF_R_SYM(rel->r_info); 115 assert(sym->st_info == 116 ELF_ST_INFO(STB_LOCAL, STT_SECTION)); 117 *where += (Elf_Addr)(sym->st_value + relocbase); 118 break; 119 120 default: 121 abort(); 122 } 123 } 124 } 125 126 /* 127 * It is possible for the compiler to emit relocations for unaligned data. 128 * We handle this situation with these inlines. 129 */ 130 #define RELOC_ALIGNED_P(x) \ 131 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) 132 133 static __inline Elf_Addr 134 load_ptr(void *where) 135 { 136 Elf_Addr res; 137 138 memcpy(&res, where, sizeof(res)); 139 140 return (res); 141 } 142 143 static __inline void 144 store_ptr(void *where, Elf_Addr val) 145 { 146 147 memcpy(where, &val, sizeof(val)); 148 } 149 150 int 151 _rtld_relocate_nonplt_objects(const Obj_Entry *obj) 152 { 153 const Elf_Rel *rel; 154 Elf_Addr *got = obj->pltgot; 155 const Elf_Sym *sym, *def; 156 const Obj_Entry *defobj; 157 int i; 158 #ifdef SUPPORT_OLD_BROKEN_LD 159 int broken; 160 #endif 161 162 #ifdef SUPPORT_OLD_BROKEN_LD 163 broken = 0; 164 sym = obj->symtab; 165 for (i = 1; i < 12; i++) 166 if (sym[i].st_info == ELF_ST_INFO(STB_LOCAL, STT_NOTYPE)) 167 broken = 1; 168 dbg(("%s: broken=%d", obj->path, broken)); 169 #endif 170 171 i = (got[1] & 0x80000000) ? 2 : 1; 172 /* Relocate the local GOT entries */ 173 got += i; 174 for (; i < obj->local_gotno; i++) 175 *got++ += (Elf_Addr)obj->relocbase; 176 sym = obj->symtab + obj->gotsym; 177 /* Now do the global GOT entries */ 178 for (i = obj->gotsym; i < obj->symtabno; i++) { 179 rdbg((" doing got %d sym %p (%s, %x)", i - obj->gotsym, sym, 180 sym->st_name + obj->strtab, *got)); 181 182 #ifdef SUPPORT_OLD_BROKEN_LD 183 if (ELF_ST_TYPE(sym->st_info) == STT_FUNC && 184 broken && sym->st_shndx == SHN_UNDEF) { 185 /* 186 * XXX DANGER WILL ROBINSON! 187 * You might think this is stupid, as it intentionally 188 * defeats lazy binding -- and you'd be right. 189 * Unfortunately, for lazy binding to work right, we 190 * need to a way to force the GOT slots used for 191 * function pointers to be resolved immediately. This 192 * is supposed to be done automatically by the linker, 193 * by not outputting a PLT slot and setting st_value 194 * to 0 if there are non-PLT references, but older 195 * versions of GNU ld do not do this. 196 */ 197 def = _rtld_find_symdef(i, obj, &defobj, false); 198 if (def == NULL) 199 return -1; 200 *got = def->st_value + (Elf_Addr)defobj->relocbase; 201 } else 202 #endif 203 if (ELF_ST_TYPE(sym->st_info) == STT_FUNC && 204 sym->st_value != 0) { 205 /* 206 * If there are non-PLT references to the function, 207 * st_value should be 0, forcing us to resolve the 208 * address immediately. 209 */ 210 *got = sym->st_value + (Elf_Addr)obj->relocbase; 211 } else if (sym->st_info == ELF_ST_INFO(STB_GLOBAL, STT_SECTION)) { 212 /* Symbols with index SHN_ABS are not relocated. */ 213 if (sym->st_shndx != SHN_ABS) 214 *got = sym->st_value + 215 (Elf_Addr)obj->relocbase; 216 } else { 217 def = _rtld_find_symdef(i, obj, &defobj, false); 218 if (def == NULL) 219 return -1; 220 *got = def->st_value + (Elf_Addr)defobj->relocbase; 221 } 222 223 rdbg((" --> now %x", *got)); 224 ++sym; 225 ++got; 226 } 227 228 got = obj->pltgot; 229 for (rel = obj->rel; rel < obj->rellim; rel++) { 230 Elf_Addr *where, tmp; 231 unsigned long symnum; 232 233 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 234 symnum = ELF_R_SYM(rel->r_info); 235 236 switch (ELF_R_TYPE(rel->r_info)) { 237 case R_TYPE(NONE): 238 break; 239 240 case R_TYPE(REL32): 241 /* 32-bit PC-relative reference */ 242 def = obj->symtab + symnum; 243 244 if (symnum >= obj->gotsym) { 245 tmp = *where; 246 tmp += got[obj->local_gotno + symnum - obj->gotsym]; 247 *where = tmp; 248 249 rdbg(("REL32/G %s in %s --> %p in %s", 250 obj->strtab + def->st_name, obj->path, 251 (void *)tmp, obj->path)); 252 break; 253 } else { 254 /* 255 * XXX: ABI DIFFERENCE! 256 * 257 * Old NetBSD binutils would generate shared 258 * libs with section-relative relocations being 259 * already adjusted for the start address of 260 * the section. 261 * 262 * New binutils, OTOH, generate shared libs 263 * with the same relocations being based at 264 * zero, so we need to add in the start address 265 * of the section. 266 * 267 * --rkb, Oct 6, 2001 268 */ 269 tmp = *where; 270 271 if (def->st_info == 272 ELF_ST_INFO(STB_LOCAL, STT_SECTION) 273 #ifdef SUPPORT_OLD_BROKEN_LD 274 && !broken 275 #endif 276 ) 277 tmp += (Elf_Addr)def->st_value; 278 279 tmp += (Elf_Addr)obj->relocbase; 280 *where = tmp; 281 282 rdbg(("REL32/L %s in %s --> %p in %s", 283 obj->strtab + def->st_name, obj->path, 284 (void *)tmp, obj->path)); 285 } 286 break; 287 288 default: 289 rdbg(("sym = %lu, type = %lu, offset = %p, " 290 "contents = %p, symbol = %s", 291 symnum, (u_long)ELF_R_TYPE(rel->r_info), 292 (void *)rel->r_offset, (void *)load_ptr(where), 293 obj->strtab + obj->symtab[symnum].st_name)); 294 _rtld_error("%s: Unsupported relocation type %ld " 295 "in non-PLT relocations\n", 296 obj->path, (u_long) ELF_R_TYPE(rel->r_info)); 297 return -1; 298 } 299 } 300 301 return 0; 302 } 303 304 int 305 _rtld_relocate_plt_lazy(const Obj_Entry *obj) 306 { 307 /* PLT fixups were done above in the GOT relocation. */ 308 return 0; 309 } 310 311 caddr_t 312 _rtld_bind(Elf_Word a0, Elf_Addr a1, Elf_Addr a2, Elf_Addr a3) 313 { 314 Elf_Addr *got = (Elf_Addr *)(a2 - 0x7ff0); 315 const Obj_Entry *obj = (Obj_Entry *)(got[1] & 0x7fffffff); 316 const Elf_Sym *def; 317 const Obj_Entry *defobj; 318 Elf_Addr new_value; 319 320 def = _rtld_find_symdef(a0, obj, &defobj, true); 321 if (def == NULL) 322 _rtld_die(); 323 324 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 325 rdbg(("bind now/fixup in %s --> new=%p", 326 defobj->strtab + def->st_name, (void *)new_value)); 327 got[obj->local_gotno + a0 - obj->gotsym] = new_value; 328 return ((caddr_t)new_value); 329 } 330
Indexes created Tue Sep 30 20:09:53 GMT 2025