mdreloc.c revision 1.15
1 /* $NetBSD: mdreloc.c,v 1.15 2002/09/05 21:21:12 mycroft Exp $ */ 2 3 /*- 4 * Copyright (c) 1999 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Paul Kranenburg. 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <errno.h> 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <unistd.h> 44 #include <sys/stat.h> 45 46 #include "rtldenv.h" 47 #include "debug.h" 48 #include "rtld.h" 49 50 /* 51 * The following table holds for each relocation type: 52 * - the width in bits of the memory location the relocation 53 * applies to (not currently used) 54 * - the number of bits the relocation value must be shifted to the 55 * right (i.e. discard least significant bits) to fit into 56 * the appropriate field in the instruction word. 57 * - flags indicating whether 58 * * the relocation involves a symbol 59 * * the relocation is relative to the current position 60 * * the relocation is for a GOT entry 61 * * the relocation is relative to the load address 62 * 63 */ 64 #define _RF_S 0x80000000 /* Resolve symbol */ 65 #define _RF_A 0x40000000 /* Use addend */ 66 #define _RF_P 0x20000000 /* Location relative */ 67 #define _RF_G 0x10000000 /* GOT offset */ 68 #define _RF_B 0x08000000 /* Load address relative */ 69 #define _RF_SZ(s) (((s) & 0xff) << 8) /* memory target size */ 70 #define _RF_RS(s) ( (s) & 0xff) /* right shift */ 71 static int reloc_target_flags[] = { 72 0, /* NONE */ 73 _RF_S|_RF_A| _RF_SZ(8) | _RF_RS(0), /* RELOC_8 */ 74 _RF_S|_RF_A| _RF_SZ(16) | _RF_RS(0), /* RELOC_16 */ 75 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* RELOC_32 */ 76 _RF_S|_RF_A|_RF_P| _RF_SZ(8) | _RF_RS(0), /* DISP_8 */ 77 _RF_S|_RF_A|_RF_P| _RF_SZ(16) | _RF_RS(0), /* DISP_16 */ 78 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* DISP_32 */ 79 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP_30 */ 80 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP_22 */ 81 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(10), /* HI22 */ 82 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 22 */ 83 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 13 */ 84 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* LO10 */ 85 _RF_G| _RF_SZ(32) | _RF_RS(0), /* GOT10 */ 86 _RF_G| _RF_SZ(32) | _RF_RS(0), /* GOT13 */ 87 _RF_G| _RF_SZ(32) | _RF_RS(10), /* GOT22 */ 88 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PC10 */ 89 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(10), /* PC22 */ 90 _RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WPLT30 */ 91 _RF_SZ(32) | _RF_RS(0), /* COPY */ 92 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* GLOB_DAT */ 93 _RF_SZ(32) | _RF_RS(0), /* JMP_SLOT */ 94 _RF_A| _RF_B| _RF_SZ(32) | _RF_RS(0), /* RELATIVE */ 95 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* UA_32 */ 96 97 /*unknown*/ _RF_SZ(32) | _RF_RS(0), /* PLT32 */ 98 /*unknown*/ _RF_SZ(32) | _RF_RS(0), /* HIPLT22 */ 99 /*unknown*/ _RF_SZ(32) | _RF_RS(0), /* LOPLT10 */ 100 /*unknown*/ _RF_SZ(32) | _RF_RS(0), /* LOPLT10 */ 101 /*unknown*/ _RF_SZ(32) | _RF_RS(0), /* PCPLT22 */ 102 /*unknown*/ _RF_SZ(32) | _RF_RS(0), /* PCPLT32 */ 103 _RF_S|_RF_A|/*unknown*/ _RF_SZ(32) | _RF_RS(0), /* 10 */ 104 _RF_S|_RF_A|/*unknown*/ _RF_SZ(32) | _RF_RS(0), /* 11 */ 105 _RF_S|_RF_A|/*unknown*/ _RF_SZ(32) | _RF_RS(0), /* 64 */ 106 _RF_S|_RF_A|/*unknown*/ _RF_SZ(32) | _RF_RS(0), /* OLO10 */ 107 _RF_S|_RF_A|/*unknown*/ _RF_SZ(32) | _RF_RS(0), /* HH22 */ 108 _RF_S|_RF_A|/*unknown*/ _RF_SZ(32) | _RF_RS(0), /* HM10 */ 109 _RF_S|_RF_A|/*unknown*/ _RF_SZ(32) | _RF_RS(0), /* LM22 */ 110 _RF_S|_RF_A|_RF_P|/*unknown*/ _RF_SZ(32) | _RF_RS(0), /* WDISP16 */ 111 _RF_S|_RF_A|_RF_P|/*unknown*/ _RF_SZ(32) | _RF_RS(0), /* WDISP19 */ 112 /*unknown*/ _RF_SZ(32) | _RF_RS(0), /* GLOB_JMP */ 113 /*unknown*/ _RF_SZ(32) | _RF_RS(0), /* 7 */ 114 /*unknown*/ _RF_SZ(32) | _RF_RS(0), /* 5 */ 115 /*unknown*/ _RF_SZ(32) | _RF_RS(0), /* 6 */ 116 }; 117 118 #ifdef RTLD_DEBUG_RELOC 119 static const char *reloc_names[] = { 120 "NONE", "RELOC_8", "RELOC_16", "RELOC_32", "DISP_8", 121 "DISP_16", "DISP_32", "WDISP_30", "WDISP_22", "HI22", 122 "22", "13", "LO10", "GOT10", "GOT13", 123 "GOT22", "PC10", "PC22", "WPLT30", "COPY", 124 "GLOB_DAT", "JMP_SLOT", "RELATIVE", "UA_32", "PLT32", 125 "HIPLT22", "LOPLT10", "LOPLT10", "PCPLT22", "PCPLT32", 126 "10", "11", "64", "OLO10", "HH22", 127 "HM10", "LM22", "WDISP16", "WDISP19", "GLOB_JMP", 128 "7", "5", "6" 129 }; 130 #endif 131 132 #define RELOC_RESOLVE_SYMBOL(t) ((reloc_target_flags[t] & _RF_S) != 0) 133 #define RELOC_PC_RELATIVE(t) ((reloc_target_flags[t] & _RF_P) != 0) 134 #define RELOC_BASE_RELATIVE(t) ((reloc_target_flags[t] & _RF_B) != 0) 135 #define RELOC_TARGET_SIZE(t) ((reloc_target_flags[t] >> 8) & 0xff) 136 #define RELOC_VALUE_RIGHTSHIFT(t) (reloc_target_flags[t] & 0xff) 137 138 static int reloc_target_bitmask[] = { 139 #define _BM(x) (~(-(1ULL << (x)))) 140 0, /* NONE */ 141 _BM(8), _BM(16), _BM(32), /* RELOC_8, _16, _32 */ 142 _BM(8), _BM(16), _BM(32), /* DISP8, DISP16, DISP32 */ 143 _BM(30), _BM(22), /* WDISP30, WDISP22 */ 144 _BM(22), _BM(22), /* HI22, _22 */ 145 _BM(13), _BM(10), /* RELOC_13, _LO10 */ 146 _BM(10), _BM(13), _BM(22), /* GOT10, GOT13, GOT22 */ 147 _BM(10), _BM(22), /* _PC10, _PC22 */ 148 _BM(30), 0, /* _WPLT30, _COPY */ 149 -1, -1, -1, /* _GLOB_DAT, JMP_SLOT, _RELATIVE */ 150 _BM(32), _BM(32), /* _UA32, PLT32 */ 151 _BM(22), _BM(10), /* _HIPLT22, LOPLT10 */ 152 _BM(32), _BM(22), _BM(10), /* _PCPLT32, _PCPLT22, _PCPLT10 */ 153 _BM(10), _BM(11), -1, /* _10, _11, _64 */ 154 _BM(10), _BM(22), /* _OLO10, _HH22 */ 155 _BM(10), _BM(22), /* _HM10, _LM22 */ 156 _BM(16), _BM(19), /* _WDISP16, _WDISP19 */ 157 -1, /* GLOB_JMP */ 158 _BM(7), _BM(5), _BM(6) /* _7, _5, _6 */ 159 #undef _BM 160 }; 161 #define RELOC_VALUE_BITMASK(t) (reloc_target_bitmask[t]) 162 163 int 164 _rtld_relocate_plt_object(obj, rela, addrp, bind_now, dodebug) 165 Obj_Entry *obj; 166 const Elf_Rela *rela; 167 caddr_t *addrp; 168 bool bind_now; 169 bool dodebug; 170 { 171 const Elf_Sym *def; 172 const Obj_Entry *defobj; 173 Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset); 174 Elf_Addr value; 175 176 if (bind_now == 0 && obj->pltgot != NULL) 177 return (0); 178 179 /* Fully resolve procedure addresses now */ 180 181 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 182 183 def = _rtld_find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true); 184 if (def == NULL) 185 return (-1); 186 187 value = (Elf_Addr) (defobj->relocbase + def->st_value); 188 189 rdbg(dodebug, ("bind now %d/fixup in %s --> old=%p new=%p", 190 (int)bind_now, defobj->strtab + def->st_name, 191 (void *)*where, (void *)value)); 192 193 /* 194 * At the PLT entry pointed at by `where', we now construct 195 * a direct transfer to the now fully resolved function 196 * address. The resulting code in the jump slot is: 197 * 198 * sethi %hi(roffset), %g1 199 * sethi %hi(addr), %g1 200 * jmp %g1+%lo(addr) 201 * 202 * We write the third instruction first, since that leaves the 203 * previous `b,a' at the second word in place. Hence the whole 204 * PLT slot can be atomically change to the new sequence by 205 * writing the `sethi' instruction at word 2. 206 */ 207 #define SETHI 0x03000000 208 #define JMP 0x81c06000 209 #define NOP 0x01000000 210 where[2] = JMP | (value & 0x000003ff); 211 where[1] = SETHI | ((value >> 10) & 0x003fffff); 212 __asm __volatile("iflush %0+8" : : "r" (where)); 213 __asm __volatile("iflush %0+4" : : "r" (where)); 214 215 if (addrp != NULL) 216 *addrp = (caddr_t)value; 217 218 return (0); 219 } 220 221 void 222 _rtld_setup_pltgot(const Obj_Entry *obj) 223 { 224 /* 225 * PLTGOT is the PLT on the sparc. 226 * The first entry holds the call the dynamic linker. 227 * We construct a `call' sequence that transfers 228 * to `_rtld_bind_start()'. 229 * The second entry holds the object identification. 230 * Note: each PLT entry is three words long. 231 */ 232 #define SAVE 0x9de3bfc0 /* i.e. `save %sp,-64,%sp' */ 233 #define CALL 0x40000000 234 #define NOP 0x01000000 235 obj->pltgot[0] = SAVE; 236 obj->pltgot[1] = CALL | 237 ((Elf_Addr) &_rtld_bind_start - (Elf_Addr) &obj->pltgot[1]) >> 2; 238 obj->pltgot[2] = NOP; 239 obj->pltgot[3] = (Elf_Addr) obj; 240 } 241 242 int 243 _rtld_relocate_nonplt_objects(obj, dodebug) 244 Obj_Entry *obj; 245 bool dodebug; 246 { 247 const Elf_Rela *rela; 248 249 for (rela = obj->rela; rela < obj->relalim; rela++) { 250 Elf_Addr *where; 251 Elf_Word type, value, mask; 252 const Elf_Sym *def = NULL; 253 const Obj_Entry *defobj = NULL; 254 unsigned long symnum; 255 256 where = (Elf_Addr *) (obj->relocbase + rela->r_offset); 257 symnum = ELF_R_SYM(rela->r_info); 258 259 type = ELF_R_TYPE(rela->r_info); 260 if (type == R_TYPE(NONE)) 261 return (0); 262 263 /* We do JMP_SLOTs in relocate_plt_object() below */ 264 if (type == R_TYPE(JMP_SLOT)) 265 return (0); 266 267 /* COPY relocs are also handled elsewhere */ 268 if (type == R_TYPE(COPY)) 269 return (0); 270 271 /* 272 * We use the fact that relocation types are an `enum' 273 * Note: R_SPARC_6 is currently numerically largest. 274 */ 275 if (type > R_TYPE(6)) 276 return (-1); 277 278 value = rela->r_addend; 279 280 /* 281 * Handle relative relocs here, because we might not 282 * be able to access globals yet. 283 */ 284 if (!dodebug && type == R_TYPE(RELATIVE)) { 285 *where += (Elf_Addr)(obj->relocbase + value); 286 return (0); 287 } 288 289 if (RELOC_RESOLVE_SYMBOL(type)) { 290 291 /* Find the symbol */ 292 def = _rtld_find_symdef(symnum, obj, &defobj, false); 293 if (def == NULL) 294 return (-1); 295 296 /* Add in the symbol's absolute address */ 297 value += (Elf_Word)(defobj->relocbase + def->st_value); 298 } 299 300 if (RELOC_PC_RELATIVE(type)) { 301 value -= (Elf_Word)where; 302 } 303 304 if (RELOC_BASE_RELATIVE(type)) { 305 /* 306 * Note that even though sparcs use `Elf_rela' 307 * exclusively we still need the implicit memory addend 308 * in relocations referring to GOT entries. 309 * Undoubtedly, someone f*cked this up in the distant 310 * past, and now we're stuck with it in the name of 311 * compatibility for all eternity.. 312 * 313 * In any case, the implicit and explicit should be 314 * mutually exclusive. We provide a check for that 315 * here. 316 */ 317 #define DIAGNOSTIC 318 #ifdef DIAGNOSTIC 319 if (value != 0 && *where != 0) { 320 xprintf("BASE_REL(%s): where=%p, *where 0x%x, " 321 "addend=0x%x, base %p\n", 322 obj->path, where, *where, 323 rela->r_addend, obj->relocbase); 324 } 325 #endif 326 value += (Elf_Word)(obj->relocbase + *where); 327 } 328 329 mask = RELOC_VALUE_BITMASK(type); 330 value >>= RELOC_VALUE_RIGHTSHIFT(type); 331 value &= mask; 332 333 /* We ignore alignment restrictions here */ 334 *where &= ~mask; 335 *where |= value; 336 #ifdef RTLD_DEBUG_RELOC 337 if (RELOC_RESOLVE_SYMBOL(type)) { 338 rdbg(dodebug, ("%s %s in %s --> %p %s", 339 reloc_names[type], 340 defobj->strtab + def->st_name, obj->path, 341 (void *)*where, defobj->path)); 342 } 343 else { 344 rdbg(dodebug, ("%s --> %p", reloc_names[type], 345 (void *)*where)); 346 } 347 #endif 348 } 349 return (0); 350 } 351
Indexes created Thu Oct 02 07:10:07 GMT 2025