ldso/ldso/m68k/elfinterp.c

   1 /* vi: set sw=4 ts=4: */
   2 /* m68k 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  * Adapted to ELF/68k by Andreas Schwab.
   7  *
   8  * All rights reserved.
   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. The name of the above contributors may not be
  16  *    used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 /* Program to load an ELF binary on a linux system, and run it.
  33    References to symbols in sharable libraries can be resolved by either
  34    an ELF sharable library or a linux style of shared library. */
  35
  36 /* Disclaimer:  I have never seen any AT&T source code for SVr4, nor have
  37    I ever taken any courses on internals.  This program was developed using
  38    information available through the book "UNIX SYSTEM V RELEASE 4,
  39    Programmers guide: Ansi C and Programming Support Tools", which did
  40    a more than adequate job of explaining everything required to get this
  41    working. */
  42
  43 #include "ldso.h"
  44
  45 extern int _dl_linux_resolve(void);
  46
  47 unsigned long
  48 _dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
  49 {
  50         ELF_RELOC *this_reloc;
  51         char *strtab;
  52         ElfW(Sym) *symtab;
  53         int symtab_index;
  54         char *rel_addr;
  55         char *new_addr;
  56         char **got_addr;
  57         ElfW(Addr) instr_addr;
  58         char *symname;
  59
  60         rel_addr = (char *)tpnt->dynamic_info[DT_JMPREL];
  61         this_reloc = (ELF_RELOC *)(rel_addr + reloc_entry);
  62         symtab_index = ELF_R_SYM(this_reloc->r_info);
  63
  64         symtab = (ElfW(Sym) *)tpnt->dynamic_info[DT_SYMTAB];
  65         strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
  66         symname = strtab + symtab[symtab_index].st_name;
  67
  68         /* Address of the jump instruction to fix up. */
  69         instr_addr = (this_reloc->r_offset + tpnt->loadaddr);
  70         got_addr = (char **)instr_addr;
  71
  72         /* Get the address of the GOT entry. */
  73         new_addr = _dl_find_hash(symname, tpnt->symbol_scope, tpnt, ELF_RTYPE_CLASS_PLT, NULL);
  74         if (unlikely(!new_addr)) {
  75                 _dl_dprintf(2, "%s: Can't resolve symbol '%s'\n", _dl_progname, symname);
  76                 _dl_exit(1);
  77         }
  78
  79 #if defined (__SUPPORT_LD_DEBUG__)
  80         if ((unsigned long)got_addr < 0x40000000) {
  81                 if (_dl_debug_bindings) {
  82                         _dl_dprintf(_dl_debug_file, "\nresolve function: %s", symname);
  83                         if (_dl_debug_detail)
  84                                 _dl_dprintf(_dl_debug_file,
  85                                             "\tpatched: %x ==> %x @ %x\n",
  86                                             *got_addr, new_addr, got_addr);
  87                 }
  88         }
  89         if (!_dl_debug_nofixups)
  90 #endif
  91                 *got_addr = new_addr;
  92
  93         return (unsigned int)new_addr;
  94 }
  95
  96 static int
  97 _dl_parse(struct elf_resolve *tpnt, struct dyn_elf *scope,
  98           unsigned long rel_addr, unsigned long rel_size,
  99           int (*reloc_fnc)(struct elf_resolve *tpnt, struct dyn_elf *scope,
 100                            ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab))
 101 {
 102         unsigned int i;
 103         char *strtab;
 104         ElfW(Sym) *symtab;
 105         ELF_RELOC *rpnt;
 106         int symtab_index;
 107
 108         /* Parse the relocation information. */
 109         rpnt = (ELF_RELOC *)rel_addr;
 110         rel_size /= sizeof(ELF_RELOC);
 111
 112         symtab = (ElfW(Sym) *)tpnt->dynamic_info[DT_SYMTAB];
 113         strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
 114
 115         for (i = 0; i < rel_size; i++, rpnt++) {
 116                 int res;
 117
 118                 symtab_index = ELF_R_SYM(rpnt->r_info);
 119
 120                 debug_sym(symtab, strtab, symtab_index);
 121                 debug_reloc(symtab, strtab, rpnt);
 122
 123                 res = reloc_fnc(tpnt, scope, rpnt, symtab, strtab);
 124
 125                 if (res == 0)
 126                         continue;
 127
 128                 _dl_dprintf(2, "\n%s: ", _dl_progname);
 129
 130                 if (symtab_index)
 131                         _dl_dprintf(2, "symbol '%s': ",
 132                                     strtab + symtab[symtab_index].st_name);
 133
 134                 if (unlikely(res < 0)) {
 135                         int reloc_type = ELF_R_TYPE(rpnt->r_info);
 136
 137                         _dl_dprintf(2, "can't handle reloc type "
 138 #if defined (__SUPPORT_LD_DEBUG__)
 139                                     "%s\n", _dl_reltypes(reloc_type));
 140 #else
 141                                     "%x\n", reloc_type);
 142 #endif
 143                         _dl_exit(-res);
 144                 } else if (unlikely(res > 0)) {
 145                         _dl_dprintf(2, "can't resolve symbol\n");
 146                         return res;
 147                 }
 148         }
 149
 150         return 0;
 151 }
 152
 153 static int
 154 _dl_do_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope,
 155              ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
 156 {
 157         int reloc_type;
 158         int symtab_index;
 159         char *symname;
 160         struct symbol_ref sym_ref;
 161         ElfW(Addr) *reloc_addr;
 162         ElfW(Addr) symbol_addr;
 163 #if defined (__SUPPORT_LD_DEBUG__)
 164         ElfW(Addr) old_val;
 165 #endif
 166
 167         reloc_addr = (ElfW(Addr)*)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
 168         reloc_type = ELF_R_TYPE(rpnt->r_info);
 169         symtab_index = ELF_R_SYM(rpnt->r_info);
 170         sym_ref.sym = &symtab[symtab_index];
 171         sym_ref.tpnt = NULL;
 172         symbol_addr = 0;
 173         symname = strtab + sym_ref.sym->st_name;
 174
 175         if (symtab_index) {
 176                 symbol_addr = (ElfW(Addr))_dl_find_hash(symname, scope, tpnt,
 177                                                             elf_machine_type_class(reloc_type), &sym_ref);
 178                 /*
 179                  * We want to allow undefined references to weak symbols - this
 180                  * might have been intentional.  We should not be linking local
 181                  * symbols here, so all bases should be covered.
 182                  */
 183                 if (unlikely(!symbol_addr && ELF_ST_BIND(sym_ref.sym->st_info) != STB_WEAK)) {
 184                         _dl_dprintf(2, "%s: can't resolve symbol '%s'\n", _dl_progname, symname);
 185                         _dl_exit(1);
 186                 }
 187         }
 188
 189 #if defined (__SUPPORT_LD_DEBUG__)
 190         old_val = *reloc_addr;
 191 #endif
 192
 193         switch (reloc_type) {
 194                 case R_68K_NONE:
 195                         break;
 196                 case R_68K_8:
 197                         *(char *) reloc_addr = symbol_addr + rpnt->r_addend;
 198                         break;
 199                 case R_68K_16:
 200                         *(short *) reloc_addr = symbol_addr + rpnt->r_addend;
 201                         break;
 202                 case R_68K_32:
 203                         *reloc_addr = symbol_addr + rpnt->r_addend;
 204                         break;
 205                 case R_68K_PC8:
 206                         *(char *) reloc_addr = (symbol_addr + rpnt->r_addend
 207                                                - (unsigned int) reloc_addr);
 208                         break;
 209                 case R_68K_PC16:
 210                         *(short *) reloc_addr = (symbol_addr + rpnt->r_addend
 211                                                 - (unsigned int) reloc_addr);
 212                         break;
 213                 case R_68K_PC32:
 214                         *reloc_addr = (symbol_addr + rpnt->r_addend
 215                                       - (unsigned int) reloc_addr);
 216                         break;
 217                 case R_68K_GLOB_DAT:
 218                 case R_68K_JMP_SLOT:
 219                         *reloc_addr = symbol_addr + rpnt->r_addend;
 220                         break;
 221                 /* handled by elf_machine_relative()
 222                 case R_68K_RELATIVE:
 223                         *reloc_addr = ((unsigned int) tpnt->loadaddr
 224                                       / * Compatibility kludge.  * /
 225                                       + (rpnt->r_addend ? : *reloc_addr));
 226                 */
 227                         break;
 228                 case R_68K_COPY:
 229                         if (symbol_addr) {
 230 #if defined (__SUPPORT_LD_DEBUG__)
 231                                 if (_dl_debug_move)
 232                                         _dl_dprintf(_dl_debug_file,
 233                                                     "\t%s move %d bytes from %x to %x\n",
 234                                                     symname, sym_ref.sym->st_size,
 235                                                     symbol_addr, reloc_addr);
 236 #endif
 237                                 _dl_memcpy ((void *) reloc_addr,
 238                                             (void *) symbol_addr,
 239                                             sym_ref.sym->st_size);
 240                         } else
 241                                 _dl_dprintf(_dl_debug_file, "no symbol_addr to copy !?\n");
 242                         break;
 243
 244                 default:
 245                         return -1;      /* Calls _dl_exit(1). */
 246         }
 247
 248 #if defined (__SUPPORT_LD_DEBUG__)
 249         if (_dl_debug_reloc && _dl_debug_detail)
 250                 _dl_dprintf(_dl_debug_file, "\tpatched: %x ==> %x @ %x\n",
 251                             old_val, *reloc_addr, reloc_addr);
 252 #endif
 253
 254         return 0;
 255 }
 256
 257 #undef LAZY_RELOC_WORKS
 258 #ifdef LAZY_RELOC_WORKS
 259 static int
 260 _dl_do_lazy_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope,
 261                   ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
 262 {
 263         int reloc_type;
 264         int symtab_index;
 265         ElfW(Addr) *reloc_addr;
 266 #if defined (__SUPPORT_LD_DEBUG__)
 267         ElfW(Addr) old_val;
 268 #endif
 269
 270         (void)scope;
 271         symtab_index = ELF_R_SYM(rpnt->r_info);
 272         (void)strtab;
 273
 274         reloc_addr = (ElfW(Addr)*)(tpnt->loadaddr + rpnt->r_offset);
 275         reloc_type = ELF_R_TYPE(rpnt->r_info);
 276
 277 #if defined (__SUPPORT_LD_DEBUG__)
 278         old_val = *reloc_addr;
 279 #endif
 280
 281         switch (reloc_type) {
 282                 case R_68K_NONE:
 283                         break;
 284                 case R_68K_JMP_SLOT:
 285                         *reloc_addr += (unsigned int) tpnt->loadaddr;
 286                         break;
 287                 default:
 288                         _dl_exit(1);
 289         }
 290
 291 #if defined (__SUPPORT_LD_DEBUG__)
 292         if (_dl_debug_reloc && _dl_debug_detail)
 293                 _dl_dprintf(_dl_debug_file, "\tpatched_lazy: %x ==> %x @ %x\n",
 294                             old_val, *reloc_addr, reloc_addr);
 295 #endif
 296
 297         return 0;
 298 }
 299 #endif
 300
 301 void
 302 _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
 303                                       unsigned long rel_addr,
 304                                       unsigned long rel_size)
 305 {
 306 #ifdef LAZY_RELOC_WORKS
 307         (void)_dl_parse(rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
 308 #else
 309         _dl_parse_relocation_information(rpnt, rel_addr, rel_size);
 310 #endif
 311 }
 312
 313 int
 314 _dl_parse_relocation_information(struct dyn_elf *rpnt,
 315                                  unsigned long rel_addr,
 316                                  unsigned long rel_size)
 317 {
 318         return _dl_parse(rpnt->dyn, rpnt->dyn->symbol_scope, rel_addr, rel_size, _dl_do_reloc);
 319 }