/* 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_PLTstatic 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