Logo Search packages:      
Sourcecode: uclibc version File versions  Download package

elfinterp.c

/* vi: set sw=4 ts=4: */
/* powerpc shared library loader suppport
 *
 * Copyright (C) 2001-2002 David A. Schleef
 * Copyright (C) 2003-2004 Erik Andersen
 * Copyright (C) 2004 Joakim Tjernlund
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. The name of the above contributors may not be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined (__SUPPORT_LD_DEBUG__)
static const char *_dl_reltypes_tab[] =
      { "R_PPC_NONE", "R_PPC_ADDR32", "R_PPC_ADDR24", "R_PPC_ADDR16",
      "R_PPC_ADDR16_LO", "R_PPC_ADDR16_HI", "R_PPC_ADDR16_HA",
      "R_PPC_ADDR14", "R_PPC_ADDR14_BRTAKEN", "R_PPC_ADDR14_BRNTAKEN",
      "R_PPC_REL24", "R_PPC_REL14", "R_PPC_REL14_BRTAKEN",
      "R_PPC_REL14_BRNTAKEN", "R_PPC_GOT16", "R_PPC_GOT16_LO",
      "R_PPC_GOT16_HI", "R_PPC_GOT16_HA", "R_PPC_PLTREL24",
      "R_PPC_COPY", "R_PPC_GLOB_DAT", "R_PPC_JMP_SLOT", "R_PPC_RELATIVE",
      "R_PPC_LOCAL24PC", "R_PPC_UADDR32", "R_PPC_UADDR16", "R_PPC_REL32",
      "R_PPC_PLT32", "R_PPC_PLTREL32", "R_PPC_PLT16_LO", "R_PPC_PLT16_HI",
      "R_PPC_PLT16_HA", "R_PPC_SDAREL16", "R_PPC_SECTOFF",
      "R_PPC_SECTOFF_LO", "R_PPC_SECTOFF_HI", "R_PPC_SECTOFF_HA",
};

static const char *
_dl_reltypes(int type)
{
  static char buf[22];
  const char *str;

  if (type >= (int)(sizeof (_dl_reltypes_tab)/sizeof(_dl_reltypes_tab[0])) ||
      NULL == (str = _dl_reltypes_tab[type]))
  {
    str =_dl_simple_ltoa( buf, (unsigned long)(type));
  }
  return str;
}

static
void debug_sym(Elf32_Sym *symtab,char *strtab,int symtab_index)
{
  if(_dl_debug_symbols)
  {
    if(symtab_index){
      _dl_dprintf(_dl_debug_file, "\n%s\n\tvalue=%x\tsize=%x\tinfo=%x\tother=%x\tshndx=%x",
              strtab + symtab[symtab_index].st_name,
              symtab[symtab_index].st_value,
              symtab[symtab_index].st_size,
              symtab[symtab_index].st_info,
              symtab[symtab_index].st_other,
              symtab[symtab_index].st_shndx);
    }
  }
}

static
void debug_reloc(Elf32_Sym *symtab,char *strtab, ELF_RELOC *rpnt)
{
  if(_dl_debug_reloc)
  {
    int symtab_index;
    const char *sym;
    symtab_index = ELF32_R_SYM(rpnt->r_info);
    sym = symtab_index ? strtab + symtab[symtab_index].st_name : "sym=0x0";

  if(_dl_debug_symbols)
        _dl_dprintf(_dl_debug_file, "\n\t");
  else
        _dl_dprintf(_dl_debug_file, "\n%s\n\t", sym);
#ifdef ELF_USES_RELOCA
    _dl_dprintf(_dl_debug_file, "%s\toffset=%x\taddend=%x",
            _dl_reltypes(ELF32_R_TYPE(rpnt->r_info)),
            rpnt->r_offset,
            rpnt->r_addend);
#else
    _dl_dprintf(_dl_debug_file, "%s\toffset=%x\n",
            _dl_reltypes(ELF32_R_TYPE(rpnt->r_info)),
            rpnt->r_offset);
#endif
  }
}
#endif

extern int _dl_linux_resolve(void);

void _dl_init_got(unsigned long *plt,struct elf_resolve *tpnt)
{
      Elf32_Word *tramp;
      Elf32_Word num_plt_entries;
      Elf32_Word data_words;
      Elf32_Word rel_offset_words;
      Elf32_Word dlrr = (Elf32_Word) _dl_linux_resolve;

      num_plt_entries = tpnt->dynamic_info[DT_PLTRELSZ] / sizeof(ELF_RELOC);
      rel_offset_words = PLT_DATA_START_WORDS(num_plt_entries);
      data_words = (Elf32_Word) (plt + rel_offset_words);
      tpnt->data_words = data_words;

      plt[PLT_LONGBRANCH_ENTRY_WORDS] = OPCODE_ADDIS_HI(11, 11, data_words);
      plt[PLT_LONGBRANCH_ENTRY_WORDS+1] = OPCODE_LWZ(11,data_words,11);

      plt[PLT_LONGBRANCH_ENTRY_WORDS+2] = OPCODE_MTCTR(11);
      plt[PLT_LONGBRANCH_ENTRY_WORDS+3] = OPCODE_BCTR();

      /* [4] */
      /* [5] */
      tramp = (Elf32_Word *) (plt + PLT_TRAMPOLINE_ENTRY_WORDS);

      /* For the long entries, subtract off data_words.  */
      tramp[0] = OPCODE_ADDIS_HI(11,11,-data_words);
      tramp[1] = OPCODE_ADDI(11,11,-data_words);

      /* Multiply index of entry by 3 (in r11).  */
      tramp[2] = OPCODE_SLWI(12,11,1);
      tramp[3] = OPCODE_ADD(11,12,11);
      if (dlrr <= 0x01fffffc || dlrr >= 0xfe000000) {
            /* Load address of link map in r12.  */
            tramp[4] = OPCODE_LI (12, (Elf32_Word) tpnt);
            tramp[5] = OPCODE_ADDIS_HI (12, 12, (Elf32_Word) tpnt);

            /* Call _dl_linux_resolve .  */
            tramp[6] = OPCODE_BA (dlrr);
      } else {
            /* Get address of _dl_linux_resolve in CTR.  */
            tramp[4] = OPCODE_LI(12,dlrr);
            tramp[5] = OPCODE_ADDIS_HI(12,12,dlrr);
            tramp[6] = OPCODE_MTCTR(12);

            /* Load address of link map in r12.  */
            tramp[7] = OPCODE_LI(12,(Elf32_Word) tpnt);
            tramp[8] = OPCODE_ADDIS_HI(12,12,(Elf32_Word) tpnt);

            /* Call _dl_linux_resolve.  */
            tramp[9] = OPCODE_BCTR();
      }
      /* [16] unused */
      /* [17] unused */

      PPC_DCBST(plt);
      PPC_DCBST(plt+4);
      PPC_DCBST(plt+8);
      PPC_DCBST(plt+12);
      PPC_DCBST(plt+16-1);
      PPC_SYNC;
      PPC_ICBI(plt);
      PPC_ICBI(plt+16-1);
      PPC_ISYNC;
}

unsigned long _dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
{
      ELF_RELOC *this_reloc;
      char *strtab;
      Elf32_Sym *symtab;
      ELF_RELOC *rel_addr;
      int symtab_index;
      char *symname;
      Elf32_Addr *reloc_addr;
      Elf32_Addr  finaladdr;
      Elf32_Sword delta;

      rel_addr = (ELF_RELOC *) (tpnt->dynamic_info[DT_JMPREL] + tpnt->loadaddr);

      this_reloc = (void *)rel_addr + reloc_entry;
      symtab_index = ELF32_R_SYM(this_reloc->r_info);

      symtab = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
      strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
      symname      = strtab + symtab[symtab_index].st_name;

#if defined (__SUPPORT_LD_DEBUG__)
      debug_sym(symtab,strtab,symtab_index);
      debug_reloc(symtab,strtab,this_reloc);

      if (unlikely(ELF32_R_TYPE(this_reloc->r_info) != R_PPC_JMP_SLOT)) {
            _dl_dprintf(2, "%s: Incorrect relocation type in jump relocation\n", _dl_progname);
            _dl_exit(1);
      };
#endif

      /* Address of dump instruction to fix up */
      reloc_addr = (Elf32_Addr *) (tpnt->loadaddr + this_reloc->r_offset);

#if defined (__SUPPORT_LD_DEBUG__)
      if(_dl_debug_reloc && _dl_debug_detail)
            _dl_dprintf(_dl_debug_file, "\n\tResolving symbol %s %x --> ", symname, (Elf32_Addr)reloc_addr);
#endif

      /* Get the address of the GOT entry */
      finaladdr = (Elf32_Addr) _dl_find_hash(symname,
                  tpnt->symbol_scope, tpnt, ELF_RTYPE_CLASS_PLT);
      if (unlikely(!finaladdr)) {
            _dl_dprintf(2, "%s: can't resolve symbol '%s'\n", _dl_progname, symname);
            _dl_exit(1);
      };
      finaladdr += this_reloc->r_addend;
#if defined (__SUPPORT_LD_DEBUG__)
      if(_dl_debug_reloc && _dl_debug_detail)
            _dl_dprintf(_dl_debug_file, "%x\n", finaladdr);
#endif
      delta = finaladdr - (Elf32_Word)reloc_addr;
      if (delta<<6>>6 == delta) {
            *reloc_addr = OPCODE_B(delta);
      } else if (finaladdr <= 0x01fffffc) {
            *reloc_addr = OPCODE_BA (finaladdr);
      } else {
            /* Warning: we don't handle double-sized PLT entries */
            Elf32_Word *plt, *data_words, index, offset;

            plt = (Elf32_Word *)(tpnt->dynamic_info[DT_PLTGOT] + tpnt->loadaddr);
            offset = reloc_addr - plt;
            index = (offset - PLT_INITIAL_ENTRY_WORDS)/2;
            data_words = (Elf32_Word *)tpnt->data_words;
            reloc_addr += 1;

            data_words[index] = finaladdr;
            PPC_SYNC;
            *reloc_addr =  OPCODE_B ((PLT_LONGBRANCH_ENTRY_WORDS - (offset+1)) * 4);
      }

      /* instructions were modified */
      PPC_DCBST(reloc_addr);
      PPC_SYNC;
      PPC_ICBI(reloc_addr);
      PPC_ISYNC;

      return finaladdr;
}

static inline int
_dl_do_reloc (struct elf_resolve *tpnt,struct dyn_elf *scope,
            ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab)
{
      int reloc_type;
      int symtab_index;
      char *symname;
      Elf32_Addr *reloc_addr;
      Elf32_Addr finaladdr;

      unsigned long symbol_addr;
#if defined (__SUPPORT_LD_DEBUG__)
      unsigned long old_val;
#endif
      reloc_addr   = (Elf32_Addr *)(intptr_t) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
      reloc_type   = ELF32_R_TYPE(rpnt->r_info);
      symbol_addr = tpnt->loadaddr; /* For R_PPC_RELATIVE */ 
      symtab_index = ELF32_R_SYM(rpnt->r_info);
      symname      = strtab + symtab[symtab_index].st_name;
      if (symtab_index) {
            symbol_addr = (unsigned long) _dl_find_hash(symname, scope, tpnt,
                                              elf_machine_type_class(reloc_type));
            /* We want to allow undefined references to weak symbols - this might
             * have been intentional.  We should not be linking local symbols
             * here, so all bases should be covered.
             */
            if (unlikely(!symbol_addr && ELF32_ST_BIND(symtab[symtab_index].st_info) != STB_WEAK)) {
                  _dl_dprintf(2, "%s: can't resolve symbol '%s'\n", _dl_progname, symname);
                  _dl_exit(1);
            };
      }
#if defined (__SUPPORT_LD_DEBUG__)
      old_val = *reloc_addr;
#endif
      finaladdr = (Elf32_Addr) (symbol_addr + rpnt->r_addend);

      switch (reloc_type) {
      case R_PPC_RELATIVE:
      case R_PPC_ADDR32:
      case R_PPC_GLOB_DAT:
            *reloc_addr = finaladdr;
            goto out_nocode; /* No code code modified */
      case R_PPC_JMP_SLOT:
      {
            Elf32_Sword delta = finaladdr - (Elf32_Word)reloc_addr;
            if (delta<<6>>6 == delta) {
                  *reloc_addr = OPCODE_B(delta);
            } else if (finaladdr <= 0x01fffffc) {
                  *reloc_addr = OPCODE_BA (finaladdr);
            } else {
                  /* Warning: we don't handle double-sized PLT entries */
                  Elf32_Word *plt, *data_words, index, offset;

                  plt = (Elf32_Word *)(tpnt->dynamic_info[DT_PLTGOT] + tpnt->loadaddr);
                  offset = reloc_addr - plt;
                  index = (offset - PLT_INITIAL_ENTRY_WORDS)/2;
                  data_words = (Elf32_Word *)tpnt->data_words;

                  data_words[index] = finaladdr;
                  reloc_addr[0] = OPCODE_LI(11,index*4);
                  reloc_addr[1] = OPCODE_B((PLT_LONGBRANCH_ENTRY_WORDS - (offset+1)) * 4);

                  /* instructions were modified */
                  PPC_DCBST(reloc_addr+1);
                  PPC_SYNC;
                  PPC_ICBI(reloc_addr+1);
            }
            break;
      }
      case R_PPC_COPY:
#if defined (__SUPPORT_LD_DEBUG__)
            if(_dl_debug_move)
                  _dl_dprintf(_dl_debug_file,"\n%s move %x bytes from %x to %x",
                            symname, symtab[symtab_index].st_size,
                            symbol_addr, reloc_addr);
#endif
            _dl_memcpy((char *) reloc_addr, (char *) finaladdr, symtab[symtab_index].st_size);
            goto out_nocode; /* No code code modified */
      case R_PPC_ADDR16_HA:
            finaladdr += 0x8000; /* fall through. */
      case R_PPC_ADDR16_HI:
            finaladdr >>= 16; /* fall through. */
      case R_PPC_ADDR16_LO:
            *(short *)reloc_addr = finaladdr;
            break;
      case R_PPC_REL24:
#if 0
            {
                  Elf32_Sword delta = finaladdr - (Elf32_Word)reloc_addr;
                  if(unlikely(delta<<6>>6 != delta)) {
                        _dl_dprintf(2, "%s: symbol '%s' R_PPC_REL24 is out of range.\n\t"
                                    "Compile shared libraries with -fPIC!\n",
                                    _dl_progname, symname);
                        _dl_exit(1);
                  }
                  *reloc_addr = (*reloc_addr & 0xfc000003) | (delta & 0x3fffffc);
                  break;
            }
#else
            _dl_dprintf(2,"R_PPC_REL24: Compile shared libraries with -fPIC!\n");
            _dl_exit(1);
#endif
      case R_PPC_NONE:
            goto out_nocode; /* No code code modified */
      default:
            _dl_dprintf(2, "%s: can't handle reloc type ", _dl_progname);
#if defined (__SUPPORT_LD_DEBUG__)
            _dl_dprintf(2, "%s ", _dl_reltypes(reloc_type));
#endif
            if (symtab_index)
                  _dl_dprintf(2, "'%s'\n", symname);
            return -1;
      };

      /* instructions were modified */
      PPC_DCBST(reloc_addr);
      PPC_SYNC;
      PPC_ICBI(reloc_addr);
      PPC_ISYNC;
 out_nocode:
#if defined (__SUPPORT_LD_DEBUG__)
      if(_dl_debug_reloc && _dl_debug_detail)
            _dl_dprintf(_dl_debug_file, "\tpatched: %x ==> %x @ %x", old_val, *reloc_addr, reloc_addr);
#endif
      return 0;
}

void _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt,
      unsigned long rel_addr, unsigned long rel_size)
{
      struct elf_resolve *tpnt = rpnt->dyn;
      Elf32_Word *plt, offset, i,  num_plt_entries, rel_offset_words;

      num_plt_entries = rel_size / sizeof(ELF_RELOC);

      rel_offset_words = PLT_DATA_START_WORDS(num_plt_entries);
      plt = (Elf32_Word *)(tpnt->dynamic_info[DT_PLTGOT] + tpnt->loadaddr);

      /* Set up the lazy PLT entries.  */
      offset = PLT_INITIAL_ENTRY_WORDS;
      i = 0;
      /* Warning: we don't handle double-sized PLT entries */
      while (i < num_plt_entries) {
            plt[offset  ] = OPCODE_LI(11, i * 4);
            plt[offset+1] = OPCODE_B((PLT_TRAMPOLINE_ENTRY_WORDS + 2 - (offset+1)) * 4);
            i++;
            offset += 2;
      }
      /* Now, we've modified code.  We need to write the changes from
         the data cache to a second-level unified cache, then make
         sure that stale data in the instruction cache is removed.
         (In a multiprocessor system, the effect is more complex.)
         Most of the PLT shouldn't be in the instruction cache, but
         there may be a little overlap at the start and the end.

         Assumes that dcbst and icbi apply to lines of 16 bytes or
         more.  Current known line sizes are 16, 32, and 128 bytes.  */
      for (i = 0; i < rel_offset_words; i += 4)
            PPC_DCBST (plt + i);
      PPC_DCBST (plt + rel_offset_words - 1);
      PPC_SYNC;
      PPC_ICBI (plt);
      PPC_ICBI (plt + rel_offset_words - 1);
      PPC_ISYNC;
}

static inline int
_dl_parse(struct elf_resolve *tpnt, struct dyn_elf *scope,
        unsigned long rel_addr, unsigned long rel_size,
        int (*reloc_fnc) (struct elf_resolve *tpnt, struct dyn_elf *scope,
                      ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab))
{
      unsigned int i;
      char *strtab;
      Elf32_Sym *symtab;
      ELF_RELOC *rpnt;
      int symtab_index;

      /* Now parse the relocation information */
      rpnt = (ELF_RELOC *)(intptr_t) (rel_addr + tpnt->loadaddr);
      rel_size = rel_size / sizeof(ELF_RELOC);

      symtab = (Elf32_Sym *)(intptr_t) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
      strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);

        for (i = 0; i < rel_size; i++, rpnt++) {
              int res;

            symtab_index = ELF32_R_SYM(rpnt->r_info);

#if defined (__SUPPORT_LD_DEBUG__)
            debug_sym(symtab,strtab,symtab_index);
            debug_reloc(symtab,strtab,rpnt);
#endif

            res = reloc_fnc (tpnt, scope, rpnt, symtab, strtab);

            if (res==0) continue;

            _dl_dprintf(2, "\n%s: ",_dl_progname);

            if (symtab_index)
              _dl_dprintf(2, "symbol '%s': ", strtab + symtab[symtab_index].st_name);

            if (unlikely(res <0))
            {
                    int reloc_type = ELF32_R_TYPE(rpnt->r_info);
#if defined (__SUPPORT_LD_DEBUG__)
                  _dl_dprintf(2, "can't handle reloc type %s\n ", _dl_reltypes(reloc_type));
#else
                  _dl_dprintf(2, "can't handle reloc type %x\n", reloc_type);
#endif
                  _dl_exit(-res);
            }
            if (unlikely(res >0))
            {
                  _dl_dprintf(2, "can't resolve symbol\n");
                  return res;
            }
        }
        return 0;
}

int _dl_parse_relocation_information(struct dyn_elf *rpnt,
      unsigned long rel_addr, unsigned long rel_size)
{
      return _dl_parse(rpnt->dyn, rpnt->dyn->symbol_scope, rel_addr, rel_size, _dl_do_reloc);
}

Generated by  Doxygen 1.6.0   Back to index