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/* On-demand PLT fixup for shared objects.

   Copyright (C) 1995-1999, 2000, 2001 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, write to the Free

   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA

   02111-1307 USA.  */

#include <alloca.h>

#include <stdlib.h>

#include <unistd.h>

#include <ldsodefs.h>

#include "dynamic-link.h"

#ifndef __attribute_used__

#define __attribute_used__

#endif

#if !defined ELF_MACHINE_NO_RELA || ELF_MACHINE_NO_REL

# define PLTREL  ElfW(Rela)

#else

# define PLTREL  ElfW(Rel)

#endif

#ifndef VERSYMIDX

# define VERSYMIDX(sym) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (sym))

#endif

/* This function is called through a special trampoline from the PLT the

   first time each PLT entry is called.  We must perform the relocation

   specified in the PLT of the given shared object, and return the resolved

   function address to the trampoline, which will restart the original call

   to that address.  Future calls will bounce directly from the PLT to the

   function.  */

#ifndef ELF_MACHINE_NO_PLT

static ElfW(Addr) __attribute__ ((regparm (2), used))

fixup (

# ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS

        ELF_MACHINE_RUNTIME_FIXUP_ARGS,

# endif

        /* GKM FIXME: Fix trampoline to pass bounds so we can do

           without the `__unbounded' qualifier.  */

       struct link_map *__unbounded l, ElfW(Word) reloc_offset)

{

  const ElfW(Sym) *const symtab

    = (const void *) D_PTR (l, l_info[DT_SYMTAB]);

  const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);

  const PLTREL *const reloc

    = (const void *) (D_PTR (l, l_info[DT_JMPREL]) + reloc_offset);

  const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];

  void *const rel_addr = (void *)(l->l_addr + reloc->r_offset);

  lookup_t result;

  ElfW(Addr) value;

  /* The use of `alloca' here looks ridiculous but it helps.  The goal is

     to prevent the function from being inlined and thus optimized out.

     There is no official way to do this so we use this trick.  gcc never

     inlines functions which use `alloca'.  */

  alloca (sizeof (int));

  /* Sanity check that we're really looking at a PLT relocation.  */

  assert (ELFW(R_TYPE)(reloc->r_info) == ELF_MACHINE_JMP_SLOT);

   /* Look up the target symbol.  If the normal lookup rules are not

      used don't look in the global scope.  */

  if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)

    {

      switch (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)

        {

        default:

          {

            const ElfW(Half) *vernum =

              (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);

            ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)];

            const struct r_found_version *version = &l->l_versions[ndx];

            if (version->hash != 0)

              {

                result = _dl_lookup_versioned_symbol (strtab + sym->st_name,

                                                      l, &sym, l->l_scope,

                                                      version,

                                                      ELF_RTYPE_CLASS_PLT, 0);

                break;

              }

          }

        case 0:

          result = _dl_lookup_symbol (strtab + sym->st_name, l, &sym,

                                      l->l_scope, ELF_RTYPE_CLASS_PLT, 0);

        }

      /* Currently result contains the base load address (or link map)

         of the object that defines sym.  Now add in the symbol

         offset.  */

      value = (sym ? LOOKUP_VALUE_ADDRESS (result) + sym->st_value : 0);

    }

  else

    {

      /* We already found the symbol.  The module (and therefore its load

         address) is also known.  */

      value = l->l_addr + sym->st_value;

#ifdef DL_LOOKUP_RETURNS_MAP

      result = l;

#endif

    }

  /* And now perhaps the relocation addend.  */

  value = elf_machine_plt_value (l, reloc, value);

  /* Finally, fix up the plt itself.  */

  if (__builtin_expect (_dl_bind_not, 0))

    return value;

  return elf_machine_fixup_plt (l, result, reloc, rel_addr, value);

}

#endif

#if !defined PROF && !defined ELF_MACHINE_NO_PLT && !__BOUNDED_POINTERS__

static ElfW(Addr) __attribute__ ((regparm (3), used))

profile_fixup (

#ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS

       ELF_MACHINE_RUNTIME_FIXUP_ARGS,

#endif

       struct link_map *l, ElfW(Word) reloc_offset, ElfW(Addr) retaddr)

{

  void (*mcount_fct) (ElfW(Addr), ElfW(Addr)) = _dl_mcount;

  ElfW(Addr) *resultp;

  lookup_t result;

  ElfW(Addr) value;

  /* The use of `alloca' here looks ridiculous but it helps.  The goal is

     to prevent the function from being inlined, and thus optimized out.

     There is no official way to do this so we use this trick.  gcc never

     inlines functions which use `alloca'.  */

  alloca (sizeof (int));

  /* This is the address in the array where we store the result of previous

     relocations.  */

  resultp = &l->l_reloc_result[reloc_offset / sizeof (PLTREL)];

  value = *resultp;

  if (value == 0)

    {

      /* This is the first time we have to relocate this object.  */

      const ElfW(Sym) *const symtab

        = (const void *) D_PTR (l, l_info[DT_SYMTAB]);

      const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);

      const PLTREL *const reloc

        = (const void *) (D_PTR (l, l_info[DT_JMPREL]) + reloc_offset);

      const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];

      /* Sanity check that we're really looking at a PLT relocation.  */

      assert (ELFW(R_TYPE)(reloc->r_info) == ELF_MACHINE_JMP_SLOT);

      /* Look up the target symbol.  If the symbol is marked STV_PROTECTED

         don't look in the global scope.  */

      if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)

        {

          switch (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)

            {

            default:

              {

                const ElfW(Half) *vernum =

                  (const void *) D_PTR (l,l_info[VERSYMIDX (DT_VERSYM)]);

                ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)];

                const struct r_found_version *version = &l->l_versions[ndx];

                if (version->hash != 0)

                  {

                    result = _dl_lookup_versioned_symbol(strtab + sym->st_name,

                                                         l, &sym, l->l_scope,

                                                         version,

                                                         ELF_RTYPE_CLASS_PLT,

                                                         0);

                    break;

                  }

              }

            case 0:

              result = _dl_lookup_symbol (strtab + sym->st_name, l, &sym,

                                          l->l_scope, ELF_RTYPE_CLASS_PLT, 0);

            }

          /* Currently result contains the base load address (or link map)

             of the object that defines sym.  Now add in the symbol

             offset.  */

          value = (sym ? LOOKUP_VALUE_ADDRESS (result) + sym->st_value : 0);

        }

      else

        {

          /* We already found the symbol.  The module (and therefore its load

             address) is also known.  */

          value = l->l_addr + sym->st_value;

#ifdef DL_LOOKUP_RETURNS_MAP

          result = l;

#endif

        }

      /* And now perhaps the relocation addend.  */

      value = elf_machine_plt_value (l, reloc, value);

      /* Store the result for later runs.  */

      if (__builtin_expect (! _dl_bind_not, 1))

        *resultp = value;

    }

  (*mcount_fct) (retaddr, value);

  return value;

}

#endif /* PROF && ELF_MACHINE_NO_PLT */

/* This macro is defined in dl-machine.h to define the entry point called

   by the PLT.  The `fixup' function above does the real work, but a little

   more twiddling is needed to get the stack right and jump to the address

   finally resolved.  */

ELF_MACHINE_RUNTIME_TRAMPOLINE