ldso/ldso/metag/elfinterp.c

   1 /*
   2  * Meta ELF shared library loader support.
   3  *
   4  * Program to load an elf binary on a linux system, and run it.
   5  * References to symbols in sharable libraries can be resolved
   6  * by either an ELF sharable library or a linux style of shared
   7  * library.
   8  *
   9  * Copyright (C) 2013, Imagination Technologies Ltd.
  10  *
  11  * Licensed under LGPL v2.1 or later, see the file COPYING.LIB in this tarball.
  12  */
  13
  14 #include "ldso.h"
  15
  16 /* Defined in resolve.S. */
  17 extern int _dl_linux_resolve(void);
  18
  19 static inline unsigned long __get_unaligned_reloc(unsigned long *addr)
  20 {
  21         char *rel_addr = (char *)addr;
  22         unsigned long val;
  23
  24         val = *rel_addr++ & 0xff;
  25         val |= (*rel_addr++ << 8) & 0x0000ff00;
  26         val |= (*rel_addr++ << 16) & 0x00ff0000;
  27         val |= (*rel_addr++ << 24) & 0xff000000;
  28
  29         return val;
  30 }
  31
  32 static inline void __put_unaligned_reloc(unsigned long *addr,
  33                                          unsigned long val)
  34 {
  35         char *rel_addr = (char *)addr;
  36
  37         *rel_addr++ = (val & 0x000000ff);
  38         *rel_addr++ = ((val & 0x0000ff00) >> 8);
  39         *rel_addr++ = ((val & 0x00ff0000) >> 16);
  40         *rel_addr++ = ((val & 0xff000000) >> 24);
  41 }
  42
  43 unsigned long
  44 _dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
  45 {
  46         int reloc_type;
  47         int symtab_index;
  48         char *strtab;
  49         char *symname;
  50         char *new_addr;
  51         char *rel_addr;
  52         char **got_addr;
  53         Elf32_Sym *symtab;
  54         ELF_RELOC *this_reloc;
  55         unsigned long instr_addr;
  56
  57         rel_addr = (char *)tpnt->dynamic_info[DT_JMPREL];
  58
  59         this_reloc = (ELF_RELOC *)(intptr_t)(rel_addr + reloc_entry);
  60         reloc_type = ELF32_R_TYPE(this_reloc->r_info);
  61         symtab_index = ELF32_R_SYM(this_reloc->r_info);
  62
  63         symtab = (Elf32_Sym *)(intptr_t)tpnt->dynamic_info[DT_SYMTAB];
  64         strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
  65         symname = strtab + symtab[symtab_index].st_name;
  66
  67         if (unlikely(reloc_type != R_METAG_JMP_SLOT)) {
  68                 _dl_dprintf(2, "%s: Incorrect relocation type in jump relocations\n",
  69                             _dl_progname);
  70                 _dl_exit(1);
  71         }
  72
  73         /* Address of the jump instruction to fix up. */
  74         instr_addr = ((unsigned long)this_reloc->r_offset +
  75                       (unsigned long)tpnt->loadaddr);
  76         got_addr = (char **)instr_addr;
  77
  78         /* Get the address of the GOT entry. */
  79         new_addr = _dl_find_hash(symname, tpnt->symbol_scope, tpnt,
  80                         ELF_RTYPE_CLASS_PLT, NULL);
  81         if (unlikely(!new_addr)) {
  82                 _dl_dprintf(2, "%s: Can't resolve symbol '%s'\n", _dl_progname, symname);
  83                 _dl_exit(1);
  84         }
  85
  86 #if defined (__SUPPORT_LD_DEBUG__)
  87         if (_dl_debug_bindings) {
  88                 _dl_dprintf(_dl_debug_file, "\nresolve function: %s", symname);
  89                 if (_dl_debug_detail)
  90                         _dl_dprintf(_dl_debug_file,
  91                                     "\n\tpatched: %x ==> %x @ %x\n",
  92                                     *got_addr, new_addr, got_addr);
  93         }
  94         if (!_dl_debug_nofixups) {
  95                 *got_addr = new_addr;
  96         }
  97 #else
  98         *got_addr = new_addr;
  99 #endif
 100
 101         return (unsigned long)new_addr;
 102 }
 103
 104 static int
 105 _dl_parse(struct elf_resolve *tpnt, struct dyn_elf *scope,
 106           unsigned long rel_addr, unsigned long rel_size,
 107           int (*reloc_fnc)(struct elf_resolve *tpnt, struct dyn_elf *scope,
 108                            ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab))
 109 {
 110         int symtab_index;
 111         unsigned int i;
 112         char *strtab;
 113         Elf32_Sym *symtab;
 114         ELF_RELOC *rpnt;
 115
 116         /* Parse the relocation information. */
 117         rpnt = (ELF_RELOC *)(intptr_t)rel_addr;
 118         rel_size /= sizeof(ELF_RELOC);
 119
 120         symtab = (Elf32_Sym *)(intptr_t)tpnt->dynamic_info[DT_SYMTAB];
 121         strtab = (char *)tpnt->dynamic_info[DT_STRTAB];
 122
 123         for (i = 0; i < rel_size; i++, rpnt++) {
 124                 int res;
 125
 126                 symtab_index = ELF32_R_SYM(rpnt->r_info);
 127
 128                 debug_sym(symtab, strtab, symtab_index);
 129                 debug_reloc(symtab, strtab, rpnt);
 130
 131                 /* Pass over to actual relocation function. */
 132                 res = reloc_fnc(tpnt, scope, rpnt, symtab, strtab);
 133
 134                 if (res == 0)
 135                         continue;
 136
 137                 _dl_dprintf(2, "\n%s: ", _dl_progname);
 138
 139                 if (symtab_index)
 140                         _dl_dprintf(2, "symbol '%s': ",
 141                                     strtab + symtab[symtab_index].st_name);
 142
 143                 if (unlikely(res < 0)) {
 144                         int reloc_type = ELF32_R_TYPE(rpnt->r_info);
 145
 146 #if defined (__SUPPORT_LD_DEBUG__)
 147                         _dl_dprintf(2, "can't handle reloc type %s\n",
 148                                     _dl_reltypes(reloc_type));
 149 #else
 150                         _dl_dprintf(2, "can't handle reloc type %x\n",
 151                                     reloc_type);
 152 #endif
 153                         _dl_exit(-res);
 154                 } else if (unlikely(res > 0)) {
 155                         _dl_dprintf(2, "can't resolve symbol\n");
 156                         return res;
 157                 }
 158         }
 159
 160         return 0;
 161 }
 162
 163 static int
 164 _dl_do_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope,
 165              ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab)
 166 {
 167         int reloc_type;
 168         int symtab_index;
 169         char *symname = NULL;
 170         unsigned long *reloc_addr;
 171         unsigned long symbol_addr;
 172 #if defined (__SUPPORT_LD_DEBUG__)
 173         unsigned long old_val;
 174 #endif
 175
 176         reloc_addr = (unsigned long *)(intptr_t)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
 177         reloc_type = ELF32_R_TYPE(rpnt->r_info);
 178         symtab_index = ELF32_R_SYM(rpnt->r_info);
 179         symbol_addr = 0;
 180         symname = strtab + symtab[symtab_index].st_name;
 181
 182         if (symtab_index) {
 183                 if (symtab[symtab_index].st_shndx != SHN_UNDEF &&
 184                     ELF32_ST_BIND(symtab[symtab_index].st_info) == STB_LOCAL) {
 185                         symbol_addr = (unsigned long)tpnt->loadaddr;
 186                 } else {
 187                   symbol_addr = (unsigned long)_dl_find_hash(symname, scope, tpnt,
 188                                                              elf_machine_type_class(reloc_type), NULL);
 189                 }
 190
 191                 if (unlikely(!symbol_addr && ELF32_ST_BIND(symtab[symtab_index].st_info) != STB_WEAK)) {
 192                         _dl_dprintf(2, "%s: can't resolve symbol '%s'\n", _dl_progname, symname);
 193                         _dl_exit(1);
 194                 };
 195
 196                 symbol_addr += rpnt->r_addend;
 197         }
 198
 199 #if defined (__SUPPORT_LD_DEBUG__)
 200         if (reloc_type != R_METAG_NONE)
 201                 old_val = __get_unaligned_reloc(reloc_addr);
 202 #endif
 203
 204         switch (reloc_type) {
 205                 case R_METAG_NONE:
 206                         break;
 207                 case R_METAG_GLOB_DAT:
 208                 case R_METAG_JMP_SLOT:
 209                 case R_METAG_ADDR32:
 210                         __put_unaligned_reloc(reloc_addr, symbol_addr);
 211                         break;
 212                 case R_METAG_COPY:
 213 #if defined (__SUPPORT_LD_DEBUG__)
 214                         if (_dl_debug_move)
 215                                 _dl_dprintf(_dl_debug_file,
 216                                             "\t%s move %d bytes from %x to %x\n",
 217                                             symname, symtab[symtab_index].st_size,
 218                                             symbol_addr, reloc_addr);
 219 #endif
 220
 221                         _dl_memcpy((char *)reloc_addr,
 222                                    (char *)symbol_addr,
 223                                    symtab[symtab_index].st_size);
 224                         break;
 225                 case R_METAG_RELATIVE:
 226                         __put_unaligned_reloc(reloc_addr,
 227                                               (unsigned long)tpnt->loadaddr +
 228                                               rpnt->r_addend);
 229                         break;
 230                 default:
 231                         return -1;      /* Calls _dl_exit(1). */
 232         }
 233
 234 #if defined (__SUPPORT_LD_DEBUG__)
 235         if (_dl_debug_reloc && _dl_debug_detail &&
 236             (reloc_type != R_METAG_NONE)) {
 237                 unsigned long new_val = __get_unaligned_reloc(reloc_addr);
 238                 _dl_dprintf(_dl_debug_file, "\tpatched: %x ==> %x @ %x\n",
 239                             old_val, new_val, reloc_addr);
 240         }
 241 #endif
 242
 243         return 0;
 244 }
 245
 246 static int
 247 _dl_do_lazy_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope,
 248                   ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab)
 249 {
 250         int reloc_type;
 251         unsigned long *reloc_addr;
 252 #if defined (__SUPPORT_LD_DEBUG__)
 253         unsigned long old_val;
 254 #endif
 255
 256         reloc_addr = (unsigned long *)(intptr_t)(tpnt->loadaddr + (unsigned long)rpnt->r_offset);
 257         reloc_type = ELF32_R_TYPE(rpnt->r_info);
 258
 259 #if defined (__SUPPORT_LD_DEBUG__)
 260         old_val = *reloc_addr;
 261 #endif
 262
 263         switch (reloc_type) {
 264                 case R_METAG_NONE:
 265                         break;
 266                 case R_METAG_JMP_SLOT:
 267                         *reloc_addr += (unsigned long)tpnt->loadaddr;
 268                         break;
 269                 default:
 270                         return -1;      /* Calls _dl_exit(1). */
 271         }
 272
 273 #if defined (__SUPPORT_LD_DEBUG__)
 274         if (_dl_debug_reloc && _dl_debug_detail)
 275                 _dl_dprintf(_dl_debug_file, "\tpatched: %x ==> %x @ %x\n",
 276                             old_val, *reloc_addr, reloc_addr);
 277 #endif
 278
 279         return 0;
 280 }
 281
 282 /* External interface to the generic part of the dynamic linker. */
 283
 284 void
 285 _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
 286                                       unsigned long rel_addr,
 287                                       unsigned long rel_size)
 288 {
 289         _dl_parse(rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
 290 }
 291
 292 int
 293 _dl_parse_relocation_information(struct dyn_elf *rpnt,
 294                                  unsigned long rel_addr,
 295                                  unsigned long rel_size)
 296 {
 297         return _dl_parse(rpnt->dyn, rpnt->dyn->symbol_scope, rel_addr,
 298                          rel_size, _dl_do_reloc);
 299 }