1 /* $NetBSD: mdreloc.c,v 1.10 2001/04/25 12:24:51 kleink 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_nonplt_object(obj, rela, dodebug) 165 Obj_Entry *obj; 166 const Elf_Rela *rela; 167 bool dodebug; 168 { 169 Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset); 170 Elf_Word type, value, mask; 171 const Elf_Sym *def = NULL; 172 const Obj_Entry *defobj = NULL; 173 174 type = ELF_R_TYPE(rela->r_info); 175 if (type == R_TYPE(NONE)) 176 return (0); 177 178 /* We do JMP_SLOTs in relocate_plt_object() below */ 179 if (type == R_TYPE(JMP_SLOT)) 180 return (0); 181 182 /* COPY relocs are also handled elsewhere */ 183 if (type == R_TYPE(COPY)) 184 return (0); 185 186 /* 187 * We use the fact that relocation types are an `enum' 188 * Note: R_SPARC_6 is currently numerically largest. 189 */ 190 if (type > R_TYPE(6)) 191 return (-1); 192 193 value = rela->r_addend; 194 195 /* 196 * Handle relative relocs here, because we might not 197 * be able to access globals yet. 198 */ 199 if (!dodebug && type == R_TYPE(RELATIVE)) { 200 *where += (Elf_Addr)(obj->relocbase + value); 201 return (0); 202 } 203 204 if (RELOC_RESOLVE_SYMBOL(type)) { 205 206 /* Find the symbol */ 207 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, 208 NULL, obj, &defobj, false); 209 if (def == NULL) 210 return (-1); 211 212 /* Add in the symbol's absolute address */ 213 value += (Elf_Word)(defobj->relocbase + def->st_value); 214 } 215 216 if (RELOC_PC_RELATIVE(type)) { 217 value -= (Elf_Word)where; 218 } 219 220 if (RELOC_BASE_RELATIVE(type)) { 221 /* 222 * Note that even though sparcs use `Elf_rela' exclusively 223 * we still need the implicit memory addend in relocations 224 * referring to GOT entries. Undoubtedly, someone f*cked 225 * this up in the distant past, and now we're stuck with 226 * it in the name of compatibility for all eternity.. 227 * 228 * In any case, the implicit and explicit should be mutually 229 * exclusive. We provide a check for that here. 230 */ 231 #define DIAGNOSTIC 232 #ifdef DIAGNOSTIC 233 if (value != 0 && *where != 0) { 234 xprintf("BASE_REL(%s): where=%p, *where 0x%x, " 235 "addend=0x%x, base %p\n", 236 obj->path, where, *where, 237 rela->r_addend, obj->relocbase); 238 } 239 #endif 240 value += (Elf_Word)(obj->relocbase + *where); 241 } 242 243 mask = RELOC_VALUE_BITMASK(type); 244 value >>= RELOC_VALUE_RIGHTSHIFT(type); 245 value &= mask; 246 247 /* We ignore alignment restrictions here */ 248 *where &= ~mask; 249 *where |= value; 250 #ifdef RTLD_DEBUG_RELOC 251 if (RELOC_RESOLVE_SYMBOL(type)) { 252 rdbg(dodebug, ("%s %s in %s --> %p %s", 253 reloc_names[type], 254 defobj->strtab + def->st_name, obj->path, 255 (void *)*where, defobj->path)); 256 } 257 else { 258 rdbg(dodebug, ("%s --> %p", reloc_names[type], 259 (void *)*where)); 260 } 261 #endif 262 return (0); 263 } 264 265 int 266 _rtld_relocate_plt_object(obj, rela, addrp, bind_now, dodebug) 267 Obj_Entry *obj; 268 const Elf_Rela *rela; 269 caddr_t *addrp; 270 bool bind_now; 271 bool dodebug; 272 { 273 const Elf_Sym *def; 274 const Obj_Entry *defobj; 275 Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset); 276 Elf_Addr value; 277 278 if (bind_now == 0 && obj->pltgot != NULL) 279 return (0); 280 281 /* Fully resolve procedure addresses now */ 282 283 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 284 285 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, 286 NULL, obj, &defobj, true); 287 if (def == NULL) 288 return (-1); 289 290 value = (Elf_Addr) (defobj->relocbase + def->st_value); 291 292 rdbg(dodebug, ("bind now %d/fixup in %s --> old=%p new=%p", 293 (int)bind_now, defobj->strtab + def->st_name, 294 (void *)*where, (void *)value)); 295 296 /* 297 * At the PLT entry pointed at by `where', we now construct 298 * a direct transfer to the now fully resolved function 299 * address. The resulting code in the jump slot is: 300 * 301 * sethi %hi(roffset), %g1 302 * sethi %hi(addr), %g1 303 * jmp %g1+%lo(addr) 304 * 305 * We write the third instruction first, since that leaves the 306 * previous `b,a' at the second word in place. Hence the whole 307 * PLT slot can be atomically change to the new sequence by 308 * writing the `sethi' instruction at word 2. 309 */ 310 #define SETHI 0x03000000 311 #define JMP 0x81c06000 312 #define NOP 0x01000000 313 where[2] = JMP | (value & 0x000003ff); 314 where[1] = SETHI | ((value >> 10) & 0x003fffff); 315 __asm __volatile("iflush %0+8" : : "r" (where)); 316 __asm __volatile("iflush %0+4" : : "r" (where)); 317 318 if (addrp != NULL) 319 *addrp = (caddr_t)value; 320 321 return (0); 322 } 323