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, tpnt->symbol_scope, tpnt, ELF_RTYPE_CLASS_PLT);
  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 *) (0x03000000 | (((unsigned int) new_addr >> 10) & 0x3fffff));
 103                 got_addr[2] = (char *) (0x81c06000 | ((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 dyn_elf *scope,
 111                 unsigned long rel_addr, unsigned long rel_size,
 112                 int (*reloc_fnc)(struct elf_resolve *tpnt, struct dyn_elf *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 dyn_elf *scope,
 168                          ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
 169 {
 170         int reloc_type;
 171         int symtab_index;
 172         char *symname;
 173         ElfW(Sym) *sym;
 174         ElfW(Addr) *reloc_addr;
 175         ElfW(Addr) symbol_addr;
 176 #if defined (__SUPPORT_LD_DEBUG__)
 177         ElfW(Addr) old_val;
 178 #endif
 179
 180         reloc_addr = (ElfW(Addr)*)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
 181         reloc_type = ELF_R_TYPE(rpnt->r_info);
 182         symtab_index = ELF_R_SYM(rpnt->r_info);
 183         sym = &symtab[symtab_index];
 184         symbol_addr = 0;
 185         symname = strtab + sym->st_name;
 186
 187         if (symtab_index) {
 188                 symbol_addr = (ElfW(Addr))_dl_find_hash(symname, scope, tpnt,
 189                                                             elf_machine_type_class(reloc_type));
 190                 /*
 191                  * We want to allow undefined references to weak symbols - this
 192                  * might have been intentional.  We should not be linking local
 193                  * symbols here, so all bases should be covered.
 194                  */
 195                 if (unlikely(!symbol_addr && ELF_ST_BIND(sym->st_info) != STB_WEAK)) {
 196                         _dl_dprintf(2, "%s: can't resolve symbol '%s'\n", _dl_progname, symname);
 197                         _dl_exit(1);
 198                 }
 199         }
 200
 201 #if defined (__SUPPORT_LD_DEBUG__)
 202         old_val = *reloc_addr;
 203 #endif
 204
 205         symbol_addr += rpnt->r_addend;  /* Assume copy relocs have zero addend.  */
 206
 207         switch (reloc_type) {
 208                 case R_SPARC_NONE:
 209                         break;
 210
 211 #if 0 /* these dont really seem to be useful */
 212                 case R_SPARC_8:
 213                         *(char *) reloc_addr = symbol_addr;
 214                         break;
 215                 case R_SPARC_16:
 216                         *(short *) reloc_addr = symbol_addr;
 217                         break;
 218                 case R_SPARC_DISP8:
 219                         *(char *) reloc_addr = (symbol_addr) - (Elf32_Addr) reloc_addr;
 220                         break;
 221                 case R_SPARC_DISP16:
 222                         *(short *) reloc_addr = (symbol_addr) - (Elf32_Addr) reloc_addr;
 223                         break;
 224 #endif
 225
 226                 case R_SPARC_DISP32:
 227                         *reloc_addr = symbol_addr - (unsigned int) reloc_addr;
 228                         break;
 229
 230                 case R_SPARC_LO10:
 231                         if (!symbol_addr)
 232                                 symbol_addr = tpnt->loadaddr + rpnt->r_addend;
 233                         else
 234                                 symbol_addr += rpnt->r_addend;
 235                         *reloc_addr = (*reloc_addr & ~0x3ff)|(symbol_addr & 0x3ff);
 236                         break;
 237
 238                 case R_SPARC_GLOB_DAT:
 239                 case R_SPARC_32:
 240                         *reloc_addr = symbol_addr;
 241                         break;
 242
 243                 case R_SPARC_JMP_SLOT:
 244 /*
 245 value = symbol_addr;
 246 value += reloc->r_addend;
 247 disp = value - reloc_addr;
 248 reloc_addr[1] = OPCODE_JMP_G1 | (value & 0x3ff);
 249 reloc_addr[0] = OPCODE_SETHI_G1 | (value >> 10);
 250                         reloc_addr[1] = OPCODE_JMP_G1 | ((symbol_addr-(Elf32_Addr)reloc_addr) & 0x3ff);
 251                         reloc_addr[0] = OPCODE_SETHI_G1 | ((symbol_addr-(Elf32_Addr)reloc_addr) >> 10);
 252 */
 253                         reloc_addr[1] = 0x03000000 | ((symbol_addr >> 10) & 0x3fffff);
 254                         reloc_addr[2] = 0x81c06000 | (symbol_addr & 0x3ff);
 255                         break;
 256
 257                 case R_SPARC_RELATIVE:
 258                         *reloc_addr += tpnt->loadaddr + rpnt->r_addend;
 259                         break;
 260
 261                 case R_SPARC_WDISP30:
 262                         *reloc_addr = (*reloc_addr & 0xc0000000)|
 263                                  ((symbol_addr - (unsigned int) reloc_addr) >> 2);
 264                         break;
 265
 266                 case R_SPARC_HI22:
 267                         if (!symbol_addr)
 268                                 symbol_addr = tpnt->loadaddr + rpnt->r_addend;
 269                         else
 270                                 symbol_addr += rpnt->r_addend;
 271                         *reloc_addr = (*reloc_addr & 0xffc00000) | (symbol_addr >> 10);
 272                         break;
 273
 274                 case R_SPARC_COPY:
 275                         if (symbol_addr) {
 276 #if defined (__SUPPORT_LD_DEBUG__)
 277                                 if (_dl_debug_move)
 278                                         _dl_dprintf(_dl_debug_file,
 279                                                     "\t%s move %d bytes from %x to %x\n",
 280                                                     symname, sym->st_size,
 281                                                     symbol_addr, reloc_addr);
 282 #endif
 283
 284                                 _dl_memcpy((char *)reloc_addr,
 285                                            (char *)symbol_addr,
 286                                            sym->st_size);
 287                         } else
 288                                 _dl_dprintf(_dl_debug_file, "no symbol_addr to copy !?\n");
 289                         break;
 290                 default:
 291                         return -1;      /* Calls _dl_exit(1). */
 292         }
 293
 294 #if defined (__SUPPORT_LD_DEBUG__)
 295         if (_dl_debug_reloc && _dl_debug_detail)
 296                 _dl_dprintf(_dl_debug_file, "\tpatched: %x ==> %x @ %x\n",
 297                             old_val, *reloc_addr, reloc_addr);
 298 #endif
 299
 300         return 0;
 301 }
 302
 303 #undef __SPARC_LAZY_RELOC_WORKS
 304 #ifdef __SPARC_LAZY_RELOC_WORKS
 305 static int
 306 _dl_do_lazy_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope,
 307                   ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
 308 {
 309         int reloc_type;
 310         int symtab_index;
 311         ElfW(Addr) *reloc_addr;
 312 #if defined (__SUPPORT_LD_DEBUG__)
 313         ElfW(Addr) old_val;
 314 #endif
 315
 316         (void)scope;
 317         symtab_index = ELF_R_SYM(rpnt->r_info);
 318         (void)strtab;
 319
 320         reloc_addr = (ElfW(Addr)*)(tpnt->loadaddr + rpnt->r_offset);
 321         reloc_type = ELF_R_TYPE(rpnt->r_info);
 322
 323 #if defined (__SUPPORT_LD_DEBUG__)
 324         old_val = *reloc_addr;
 325 #endif
 326
 327         switch (reloc_type) {
 328                 case R_SPARC_NONE:
 329                         break;
 330                 case R_SPARC_JMP_SLOT:
 331                         break;
 332                 default:
 333                         _dl_exit(1);
 334         }
 335
 336 #if defined (__SUPPORT_LD_DEBUG__)
 337         if (_dl_debug_reloc && _dl_debug_detail)
 338                 _dl_dprintf(_dl_debug_file, "\tpatched_lazy: %x ==> %x @ %x\n",
 339                             old_val, *reloc_addr, reloc_addr);
 340 #endif
 341
 342         return 0;
 343 }
 344 #endif
 345
 346 void
 347 _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
 348                                       unsigned long rel_addr,
 349                                       unsigned long rel_size)
 350 {
 351 #ifdef __SPARC_LAZY_RELOC_WORKS
 352         (void)_dl_parse(rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
 353 #else
 354         _dl_parse_relocation_information(rpnt, rel_addr, rel_size);
 355 #endif
 356 }
 357
 358 int
 359 _dl_parse_relocation_information(struct dyn_elf *rpnt,
 360                                  unsigned long rel_addr,
 361                                  unsigned long rel_size)
 362 {
 363         return _dl_parse(rpnt->dyn, rpnt->dyn->symbol_scope, rel_addr, rel_size, _dl_do_reloc);
 364 }