ldso/ldso/sparc/elfinterp.c

   1 /* vi: set sw=4 ts=4: */
   2 /* sparc ELF shared library loader suppport
   3  *
   4  * Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
   5  *                              David Engel, Hongjiu Lu and Mitch D'Souza
   6  *
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. The name of the above contributors may not be
  15  *    used to endorse or promote products derived from this software
  16  *    without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  */
  30
  31 /* Program to load an ELF binary on a linux system, and run it.
  32 References to symbols in sharable libraries can be resolved by either
  33 an ELF sharable library or a linux style of shared library. */
  34
  35 /* Disclaimer:  I have never seen any AT&T source code for SVr4, nor have
  36          I ever taken any courses on internals.  This program was developed using
  37          information available through the book "UNIX SYSTEM V RELEASE 4,
  38          Programmers guide: Ansi C and Programming Support Tools", which did
  39          a more than adequate job of explaining everything required to get this
  40          working. */
  41
  42 /* Some SPARC opcodes we need to use for self-modifying code.  */
  43 #define OPCODE_NOP      0x01000000 /* nop */
  44 #define OPCODE_CALL     0x40000000 /* call ?; add PC-rel word address */
  45 #define OPCODE_SETHI_G1 0x03000000 /* sethi ?, %g1; add value>>10 */
  46 #define OPCODE_JMP_G1   0x81c06000 /* jmp %g1+?; add lo 10 bits of value */
  47 #define OPCODE_SAVE_SP  0x9de3bfa8 /* save %sp, -(16+6)*4, %sp */
  48 #define OPCODE_BA       0x30800000 /* b,a ?; add PC-rel word address */
  49
  50 extern int _dl_linux_resolve(void);
  51
  52 unsigned long
  53 _dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
  54 {
  55         ELF_RELOC *this_reloc;
  56         char *strtab;
  57         ElfW(Sym) *symtab;
  58         int symtab_index;
  59         char *rel_addr;
  60         char *new_addr;
  61         char **got_addr;
  62         ElfW(Addr) instr_addr;
  63         char *symname;
  64
  65         rel_addr = (char *)tpnt->dynamic_info[DT_JMPREL];
  66         /*
  67          * Generate the correct relocation index into the .rela.plt section.
  68          */
  69         reloc_entry = (reloc_entry >> 10) - 0xc;
  70
  71         this_reloc = (ELF_RELOC *)(rel_addr + reloc_entry);
  72         symtab_index = ELF_R_SYM(this_reloc->r_info);
  73
  74         symtab = (ElfW(Sym) *)tpnt->dynamic_info[DT_SYMTAB];
  75         strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
  76         symname = strtab + symtab[symtab_index].st_name;
  77
  78         /* Address of the jump instruction to fix up. */
  79         instr_addr = (this_reloc->r_offset + tpnt->loadaddr);
  80         got_addr = (char **)instr_addr;
  81
  82         /* Get the address of the GOT entry */
  83         new_addr = _dl_find_hash(symname, &_dl_loaded_modules->symbol_scope, tpnt, NULL, ELF_RTYPE_CLASS_PLT, NULL);
  84         if (unlikely(!new_addr)) {
  85                 _dl_dprintf(2, "%s: Can't resolve symbol '%s'\n", _dl_progname, symname);
  86                 _dl_exit(1);
  87         }
  88
  89 #if defined (__SUPPORT_LD_DEBUG__)
  90         if ((unsigned long)got_addr < 0x40000000) {
  91                 if (_dl_debug_bindings) {
  92                         _dl_dprintf(_dl_debug_file, "\nresolve function: %s", symname);
  93                         if (_dl_debug_detail)
  94                                 _dl_dprintf(_dl_debug_file,
  95                                             "\tpatched: %x ==> %x @ %x\n",
  96                                             *got_addr, new_addr, got_addr);
  97                 }
  98         }
  99         if (!_dl_debug_nofixups)
 100 #endif
 101         {
 102                 got_addr[1] = (char *) (OPCODE_SETHI_G1 | (((unsigned int) new_addr >> 10) & 0x3fffff));
 103                 got_addr[2] = (char *) (OPCODE_JMP_G1 | ((unsigned int) new_addr & 0x3ff));
 104         }
 105
 106         return (unsigned long)new_addr;
 107 }
 108
 109 static int
 110 _dl_parse(struct elf_resolve *tpnt, struct r_scope_elem *scope,
 111                 unsigned long rel_addr, unsigned long rel_size,
 112                 int (*reloc_fnc)(struct elf_resolve *tpnt, struct r_scope_elem *scope,
 113                            ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab))
 114 {
 115         unsigned int i;
 116         char *strtab;
 117         ElfW(Sym) *symtab;
 118         ELF_RELOC *rpnt;
 119         int symtab_index;
 120
 121         /* Parse the relocation information. */
 122         rpnt = (ELF_RELOC *)rel_addr;
 123         rel_size /= sizeof(ELF_RELOC);
 124
 125         symtab = (ElfW(Sym) *)tpnt->dynamic_info[DT_SYMTAB];
 126         strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
 127
 128         for (i = 0; i < rel_size; i++, rpnt++) {
 129                 int res;
 130
 131                 symtab_index = ELF_R_SYM(rpnt->r_info);
 132
 133                 debug_sym(symtab, strtab, symtab_index);
 134                 debug_reloc(symtab, strtab, rpnt);
 135
 136                 res = reloc_fnc(tpnt, scope, rpnt, symtab, strtab);
 137
 138                 if (res == 0)
 139                         continue;
 140
 141                 _dl_dprintf(2, "\n%s: ", _dl_progname);
 142
 143                 if (symtab_index)
 144                         _dl_dprintf(2, "symbol '%s': ",
 145                                     strtab + symtab[symtab_index].st_name);
 146
 147                 if (unlikely(res < 0)) {
 148                         int reloc_type = ELF_R_TYPE(rpnt->r_info);
 149
 150                         _dl_dprintf(2, "can't handle reloc type "
 151 #if defined (__SUPPORT_LD_DEBUG__)
 152                                     "%s\n", _dl_reltypes(reloc_type));
 153 #else
 154                                     "%x\n", reloc_type);
 155 #endif
 156                         _dl_exit(-res);
 157                 } else if (unlikely(res > 0)) {
 158                         _dl_dprintf(2, "can't resolve symbol\n");
 159                         return res;
 160                 }
 161         }
 162
 163         return 0;
 164 }
 165
 166 static int
 167 _dl_do_reloc(struct elf_resolve *tpnt, struct r_scope_elem *scope,
 168                          ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
 169 {
 170         int reloc_type;
 171         int symtab_index;
 172         char *symname;
 173         struct elf_resolve *tls_tpnt = 0;
 174         ElfW(Sym) *sym;
 175         ElfW(Addr) *reloc_addr;
 176         ElfW(Addr) symbol_addr;
 177 #if defined (__SUPPORT_LD_DEBUG__)
 178         ElfW(Addr) old_val;
 179 #endif
 180
 181         struct sym_val current_value = { NULL, NULL };
 182
 183         reloc_addr = (ElfW(Addr)*)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
 184         reloc_type = ELF_R_TYPE(rpnt->r_info);
 185         symtab_index = ELF_R_SYM(rpnt->r_info);
 186         sym = &symtab[symtab_index];
 187         symbol_addr = 0;
 188         symname = strtab + sym->st_name;
 189
 190         if (symtab_index) {
 191                 symbol_addr = (ElfW(Addr))_dl_find_hash(symname, scope, tpnt, &current_value,
 192                                                             elf_machine_type_class(reloc_type), &tls_tpnt);
 193                 /*
 194                  * We want to allow undefined references to weak symbols - this
 195                  * might have been intentional.  We should not be linking local
 196                  * symbols here, so all bases should be covered.
 197                  */
 198                 if (unlikely(!symbol_addr && (ELF_ST_TYPE(sym->st_info) != STT_TLS)
 199                     && (ELF_ST_BIND(sym->st_info) != STB_WEAK))) {
 200                         /* This may be non-fatal if called from dlopen. */
 201                         return 1;
 202
 203                 }
 204                 if (_dl_trace_prelink)
 205                         _dl_debug_lookup (symname, tpnt, &symtab[symtab_index],
 206                                                 &current_value, elf_machine_type_class(reloc_type));
 207         } else {
 208                 /* Relocs against STN_UNDEF are usually treated as using a
 209                  * symbol value of zero, and using the module containing the
 210                  * reloc itself. */
 211                 symbol_addr = sym->st_value;
 212                 tls_tpnt = tpnt;
 213         }
 214
 215 #if defined (__SUPPORT_LD_DEBUG__)
 216         old_val = *reloc_addr;
 217 #endif
 218
 219         symbol_addr += rpnt->r_addend;  /* Assume copy relocs have zero addend.  */
 220
 221         switch (reloc_type) {
 222                 case R_SPARC_NONE:
 223                         break;
 224
 225                 case R_SPARC_DISP32:
 226                         *reloc_addr = symbol_addr - (unsigned int) reloc_addr;
 227                         break;
 228
 229                 case R_SPARC_LO10:
 230                         if (!symbol_addr)
 231                                 symbol_addr = tpnt->loadaddr + rpnt->r_addend;
 232                         else
 233                                 symbol_addr += rpnt->r_addend;
 234                         *reloc_addr = (*reloc_addr & ~0x3ff) | (symbol_addr & 0x3ff);
 235                         break;
 236
 237                 case R_SPARC_GLOB_DAT:
 238                 case R_SPARC_32:
 239                         *reloc_addr = symbol_addr;
 240                         break;
 241
 242                 case R_SPARC_JMP_SLOT:
 243                         reloc_addr[1] = OPCODE_SETHI_G1 | (( symbol_addr >> 10 ) & 0x3fffff);
 244                         reloc_addr[2] = OPCODE_JMP_G1 | ( symbol_addr & 0x3ff );
 245                         break;
 246
 247                 case R_SPARC_RELATIVE:
 248                         *reloc_addr += tpnt->loadaddr + rpnt->r_addend;
 249                         break;
 250
 251                 case R_SPARC_WDISP30:
 252                         *reloc_addr = (*reloc_addr & 0xc0000000)|
 253                                  ((symbol_addr - (unsigned int) reloc_addr) >> 2);
 254                         break;
 255
 256                 case R_SPARC_HI22:
 257                         if (!symbol_addr)
 258                                 symbol_addr = tpnt->loadaddr + rpnt->r_addend;
 259                         else
 260                                 symbol_addr += rpnt->r_addend;
 261                         *reloc_addr = (*reloc_addr & 0xffc00000) | (symbol_addr >> 10);
 262                         break;
 263
 264                 case R_SPARC_COPY:
 265                         if (symbol_addr) {
 266 #if defined (__SUPPORT_LD_DEBUG__)
 267                                 if (_dl_debug_move)
 268                                         _dl_dprintf(_dl_debug_file,
 269                                                     "\t%s move %d bytes from %x to %x\n",
 270                                                     symname, sym->st_size,
 271                                                     symbol_addr, reloc_addr);
 272 #endif
 273
 274                                 _dl_memcpy((char *)reloc_addr,
 275                                            (char *)symbol_addr,
 276                                            sym->st_size);
 277                         } else
 278                                 _dl_dprintf(_dl_debug_file, "no symbol_addr to copy !?\n");
 279                         break;
 280 #if defined USE_TLS && USE_TLS
 281                 case R_SPARC_TLS_DTPMOD32:
 282                         *reloc_addr = tls_tpnt->l_tls_modid;
 283                         break;
 284
 285                 case R_SPARC_TLS_DTPOFF32:
 286                         /* During relocation all TLS symbols are defined and used.
 287                          * Therefore the offset is already correct.  */
 288                         *reloc_addr = sym->st_value + rpnt->r_addend;
 289                         break;
 290
 291                 case R_SPARC_TLS_TPOFF32:
 292                         /* The offset is negative, forward from the thread pointer.
 293                          * We know the offset of the object the symbol is contained in.
 294                          * It is a negative value which will be added to the
 295                          * thread pointer.  */
 296                         CHECK_STATIC_TLS ((struct link_map *) tls_tpnt);
 297                         *reloc_addr = sym->st_value - tls_tpnt->l_tls_offset + rpnt->r_addend;
 298                         break;
 299 #endif
 300                 default:
 301                         return -1;      /* Calls _dl_exit(1). */
 302         }
 303
 304 #if defined (__SUPPORT_LD_DEBUG__)
 305         if (_dl_debug_reloc && _dl_debug_detail)
 306                 _dl_dprintf(_dl_debug_file, "\tpatched: %x ==> %x @ %x\n",
 307                             old_val, *reloc_addr, reloc_addr);
 308 #endif
 309
 310         return 0;
 311 }
 312
 313 #undef __SPARC_LAZY_RELOC_WORKS
 314 #ifdef __SPARC_LAZY_RELOC_WORKS
 315 static int
 316 _dl_do_lazy_reloc(struct elf_resolve *tpnt, struct r_scope_elem *scope,
 317                   ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
 318 {
 319         int reloc_type;
 320         int symtab_index;
 321         ElfW(Addr) *reloc_addr;
 322 #if defined (__SUPPORT_LD_DEBUG__)
 323         ElfW(Addr) old_val;
 324 #endif
 325
 326         (void)scope;
 327         symtab_index = ELF_R_SYM(rpnt->r_info);
 328         (void)strtab;
 329
 330         reloc_addr = (ElfW(Addr)*)(tpnt->loadaddr + rpnt->r_offset);
 331         reloc_type = ELF_R_TYPE(rpnt->r_info);
 332
 333 #if defined (__SUPPORT_LD_DEBUG__)
 334         old_val = *reloc_addr;
 335 #endif
 336
 337         switch (reloc_type) {
 338                 case R_SPARC_NONE:
 339                         break;
 340                 case R_SPARC_JMP_SLOT:
 341                         break;
 342                 default:
 343                         _dl_exit(1);
 344         }
 345
 346 #if defined (__SUPPORT_LD_DEBUG__)
 347         if (_dl_debug_reloc && _dl_debug_detail)
 348                 _dl_dprintf(_dl_debug_file, "\tpatched_lazy: %x ==> %x @ %x\n",
 349                             old_val, *reloc_addr, reloc_addr);
 350 #endif
 351
 352         return 0;
 353 }
 354 #endif
 355
 356 void
 357 _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
 358                                       unsigned long rel_addr,
 359                                       unsigned long rel_size)
 360 {
 361 #ifdef __SPARC_LAZY_RELOC_WORKS
 362         (void)_dl_parse(rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
 363 #else
 364         _dl_parse_relocation_information(rpnt, &_dl_loaded_modules->symbol_scope,
 365                                                                         rel_addr, rel_size);
 366 #endif
 367 }
 368
 369 int
 370 _dl_parse_relocation_information(struct dyn_elf *rpnt,
 371                                  struct r_scope_elem *scope,
 372                                  unsigned long rel_addr,
 373                                  unsigned long rel_size)
 374 {
 375         return _dl_parse(rpnt->dyn, scope, rel_addr, rel_size, _dl_do_reloc);
 376 }