mdreloc.c revision 1.30
1/* $NetBSD: mdreloc.c,v 1.30 2002/09/26 02:05:41 mycroft Exp $ */ 2 3/*- 4 * Copyright (c) 1999, 2002 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 and by Charles M. Hannum. 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 */ 71static const 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 119static 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 138static const 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 163void _rtld_bind_start(void); 164void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 165caddr_t _rtld_bind __P((const Obj_Entry *, Elf_Word)); 166 167void 168_rtld_setup_pltgot(const Obj_Entry *obj) 169{ 170 /* 171 * PLTGOT is the PLT on the sparc. 172 * The first entry holds the call the dynamic linker. 173 * We construct a `call' sequence that transfers 174 * to `_rtld_bind_start()'. 175 * The second entry holds the object identification. 176 * Note: each PLT entry is three words long. 177 */ 178#define SAVE 0x9de3bfa0 /* i.e. `save %sp,-96,%sp' */ 179#define CALL 0x40000000 180#define NOP 0x01000000 181 obj->pltgot[0] = SAVE; 182 obj->pltgot[1] = CALL | 183 ((Elf_Addr) &_rtld_bind_start - (Elf_Addr) &obj->pltgot[1]) >> 2; 184 obj->pltgot[2] = NOP; 185 obj->pltgot[3] = (Elf_Addr) obj; 186} 187 188void 189_rtld_relocate_nonplt_self(dynp, relocbase) 190 Elf_Dyn *dynp; 191 Elf_Addr relocbase; 192{ 193 const Elf_Rela *rela = 0, *relalim; 194 Elf_Addr relasz = 0; 195 Elf_Addr *where; 196 197 for (; dynp->d_tag != DT_NULL; dynp++) { 198 switch (dynp->d_tag) { 199 case DT_RELA: 200 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); 201 break; 202 case DT_RELASZ: 203 relasz = dynp->d_un.d_val; 204 break; 205 } 206 } 207 relalim = (const Elf_Rela *)((caddr_t)rela + relasz); 208 for (; rela < relalim; rela++) { 209 where = (Elf_Addr *)(relocbase + rela->r_offset); 210 *where += (Elf_Addr)(relocbase + rela->r_addend); 211 } 212} 213 214int 215_rtld_relocate_nonplt_objects(obj, self) 216 const Obj_Entry *obj; 217 bool self; 218{ 219 const Elf_Rela *rela; 220 221 if (self) 222 return (0); 223 224 for (rela = obj->rela; rela < obj->relalim; rela++) { 225 Elf_Addr *where; 226 Elf_Word type, value, mask; 227 const Elf_Sym *def = NULL; 228 const Obj_Entry *defobj = NULL; 229 unsigned long symnum; 230 231 where = (Elf_Addr *) (obj->relocbase + rela->r_offset); 232 symnum = ELF_R_SYM(rela->r_info); 233 234 type = ELF_R_TYPE(rela->r_info); 235 if (type == R_TYPE(NONE)) 236 continue; 237 238 /* We do JMP_SLOTs in _rtld_bind() below */ 239 if (type == R_TYPE(JMP_SLOT)) 240 continue; 241 242 /* COPY relocs are also handled elsewhere */ 243 if (type == R_TYPE(COPY)) 244 continue; 245 246 /* 247 * We use the fact that relocation types are an `enum' 248 * Note: R_SPARC_6 is currently numerically largest. 249 */ 250 if (type > R_TYPE(6)) 251 return (-1); 252 253 value = rela->r_addend; 254 255 /* 256 * Handle relative relocs here, as an optimization. 257 */ 258 if (type == R_TYPE(RELATIVE)) { 259 *where += (Elf_Addr)(obj->relocbase + value); 260 rdbg(("RELATIVE in %s --> %p", obj->path, 261 (void *)*where)); 262 continue; 263 } 264 265 if (RELOC_RESOLVE_SYMBOL(type)) { 266 267 /* Find the symbol */ 268 def = _rtld_find_symdef(symnum, obj, &defobj, false); 269 if (def == NULL) 270 return (-1); 271 272 /* Add in the symbol's absolute address */ 273 value += (Elf_Word)(defobj->relocbase + def->st_value); 274 } 275 276 if (RELOC_PC_RELATIVE(type)) { 277 value -= (Elf_Word)where; 278 } 279 280 if (RELOC_BASE_RELATIVE(type)) { 281 /* 282 * Note that even though sparcs use `Elf_rela' 283 * exclusively we still need the implicit memory addend 284 * in relocations referring to GOT entries. 285 * Undoubtedly, someone f*cked this up in the distant 286 * past, and now we're stuck with it in the name of 287 * compatibility for all eternity.. 288 * 289 * In any case, the implicit and explicit should be 290 * mutually exclusive. We provide a check for that 291 * here. 292 */ 293#define DIAGNOSTIC 294#ifdef DIAGNOSTIC 295 if (value != 0 && *where != 0) { 296 xprintf("BASE_REL(%s): where=%p, *where 0x%x, " 297 "addend=0x%x, base %p\n", 298 obj->path, where, *where, 299 rela->r_addend, obj->relocbase); 300 } 301#endif 302 value += (Elf_Word)(obj->relocbase + *where); 303 } 304 305 mask = RELOC_VALUE_BITMASK(type); 306 value >>= RELOC_VALUE_RIGHTSHIFT(type); 307 value &= mask; 308 309 /* We ignore alignment restrictions here */ 310 *where &= ~mask; 311 *where |= value; 312#ifdef RTLD_DEBUG_RELOC 313 if (RELOC_RESOLVE_SYMBOL(type)) { 314 rdbg(("%s %s in %s --> %p in %s", reloc_names[type], 315 obj->strtab + obj->symtab[symnum].st_name, 316 obj->path, (void *)*where, defobj->path)); 317 } else { 318 rdbg(("%s in %s --> %p", reloc_names[type], 319 obj->path, (void *)*where)); 320 } 321#endif 322 } 323 return (0); 324} 325 326int 327_rtld_relocate_plt_lazy(obj) 328 const Obj_Entry *obj; 329{ 330 return (0); 331} 332 333caddr_t 334_rtld_bind(obj, reloff) 335 const Obj_Entry *obj; 336 Elf_Word reloff; 337{ 338 const Elf_Rela *rela = (const Elf_Rela *)((caddr_t)obj->pltrela + reloff); 339 const Elf_Sym *def; 340 const Obj_Entry *defobj; 341 Elf_Word *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 342 Elf_Addr value; 343 344 /* Fully resolve procedure addresses now */ 345 346 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 347 348 def = _rtld_find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true); 349 if (def == NULL) 350 _rtld_die(); 351 352 value = (Elf_Addr)(defobj->relocbase + def->st_value); 353 rdbg(("bind now/fixup in %s --> old=%p new=%p", 354 defobj->strtab + def->st_name, (void *)*where, (void *)value)); 355 356 /* 357 * At the PLT entry pointed at by `where', we now construct 358 * a direct transfer to the now fully resolved function 359 * address. The resulting code in the jump slot is: 360 * 361 * sethi %hi(roffset), %g1 362 * sethi %hi(addr), %g1 363 * jmp %g1+%lo(addr) 364 * 365 * We write the third instruction first, since that leaves the 366 * previous `b,a' at the second word in place. Hence the whole 367 * PLT slot can be atomically change to the new sequence by 368 * writing the `sethi' instruction at word 2. 369 */ 370#define SETHI 0x03000000 371#define JMP 0x81c06000 372#define NOP 0x01000000 373 where[2] = JMP | (value & 0x000003ff); 374 where[1] = SETHI | ((value >> 10) & 0x003fffff); 375 __asm __volatile("iflush %0+8" : : "r" (where)); 376 __asm __volatile("iflush %0+4" : : "r" (where)); 377 378 return (caddr_t)value; 379} 380