mips_reloc.c revision 1.41
1 /* $NetBSD: mips_reloc.c,v 1.41 2003/09/24 09:55:35 mycroft 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 && sym->st_shndx == SHN_UNDEF) { 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 * XXX DANGER WILL ROBINSON! 211 * The linker is not outputting PLT slots for calls to 212 * functions that are defined in the same shared 213 * library. This is a bug. For now, if there is a 214 * definition, we fail the test above and do not do 215 * lazy binding for this GOT slot. Unfortunately, a 216 * similar problem also seems to happen with references 217 * to data items, and we can't fix that here. 218 * - mycroft, 2003/09/24 219 */ 220 *got = sym->st_value + (Elf_Addr)obj->relocbase; 221 } else if (sym->st_info == ELF_ST_INFO(STB_GLOBAL, STT_SECTION)) { 222 /* Symbols with index SHN_ABS are not relocated. */ 223 if (sym->st_shndx != SHN_ABS) 224 *got = sym->st_value + 225 (Elf_Addr)obj->relocbase; 226 } else { 227 def = _rtld_find_symdef(i, obj, &defobj, false); 228 if (def == NULL) 229 return -1; 230 *got = def->st_value + (Elf_Addr)defobj->relocbase; 231 } 232 233 rdbg((" --> now %x", *got)); 234 ++sym; 235 ++got; 236 } 237 238 got = obj->pltgot; 239 for (rel = obj->rel; rel < obj->rellim; rel++) { 240 Elf_Addr *where, tmp; 241 unsigned long symnum; 242 243 where = (Elf_Addr *)(obj->relocbase + rel->r_offset); 244 symnum = ELF_R_SYM(rel->r_info); 245 246 switch (ELF_R_TYPE(rel->r_info)) { 247 case R_TYPE(NONE): 248 break; 249 250 case R_TYPE(REL32): 251 /* 32-bit PC-relative reference */ 252 def = obj->symtab + symnum; 253 254 if (symnum >= obj->gotsym) { 255 tmp = *where; 256 tmp += got[obj->local_gotno + symnum - obj->gotsym]; 257 *where = tmp; 258 259 rdbg(("REL32/G %s in %s --> %p in %s", 260 obj->strtab + def->st_name, obj->path, 261 (void *)tmp, obj->path)); 262 break; 263 } else { 264 /* 265 * XXX: ABI DIFFERENCE! 266 * 267 * Old NetBSD binutils would generate shared 268 * libs with section-relative relocations being 269 * already adjusted for the start address of 270 * the section. 271 * 272 * New binutils, OTOH, generate shared libs 273 * with the same relocations being based at 274 * zero, so we need to add in the start address 275 * of the section. 276 * 277 * --rkb, Oct 6, 2001 278 */ 279 tmp = *where; 280 281 if (def->st_info == 282 ELF_ST_INFO(STB_LOCAL, STT_SECTION) 283 #ifdef SUPPORT_OLD_BROKEN_LD 284 && !broken 285 #endif 286 ) 287 tmp += (Elf_Addr)def->st_value; 288 289 tmp += (Elf_Addr)obj->relocbase; 290 *where = tmp; 291 292 rdbg(("REL32/L %s in %s --> %p in %s", 293 obj->strtab + def->st_name, obj->path, 294 (void *)tmp, obj->path)); 295 } 296 break; 297 298 default: 299 rdbg(("sym = %lu, type = %lu, offset = %p, " 300 "contents = %p, symbol = %s", 301 symnum, (u_long)ELF_R_TYPE(rel->r_info), 302 (void *)rel->r_offset, (void *)load_ptr(where), 303 obj->strtab + obj->symtab[symnum].st_name)); 304 _rtld_error("%s: Unsupported relocation type %ld " 305 "in non-PLT relocations\n", 306 obj->path, (u_long) ELF_R_TYPE(rel->r_info)); 307 return -1; 308 } 309 } 310 311 return 0; 312 } 313 314 int 315 _rtld_relocate_plt_lazy(const Obj_Entry *obj) 316 { 317 /* PLT fixups were done above in the GOT relocation. */ 318 return 0; 319 } 320 321 caddr_t 322 _rtld_bind(Elf_Word a0, Elf_Addr a1, Elf_Addr a2, Elf_Addr a3) 323 { 324 Elf_Addr *got = (Elf_Addr *)(a2 - 0x7ff0); 325 const Obj_Entry *obj = (Obj_Entry *)(got[1] & 0x7fffffff); 326 const Elf_Sym *def; 327 const Obj_Entry *defobj; 328 Elf_Addr new_value; 329 330 def = _rtld_find_symdef(a0, obj, &defobj, true); 331 if (def == NULL) 332 _rtld_die(); 333 334 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 335 rdbg(("bind now/fixup in %s --> new=%p", 336 defobj->strtab + def->st_name, (void *)new_value)); 337 got[obj->local_gotno + a0 - obj->gotsym] = new_value; 338 return ((caddr_t)new_value); 339 } 340
Indexes created Tue Sep 30 20:09:53 GMT 2025