* elf/dl-lookup.c (dl_new_hash): New functions.cvs/fedora-glibc-20060710T2206

	(_dl_lookup_symbol_x): Rename hash to old_hash and don't compute
	value here.  Compute new-style hash value.  Pass new hash value
	and reference to variable with the old value to do_lookup_x.
	(_dl_setup_hash): If DT_GNU_HASH is defined, use it and not
	old-style hash table.
	(_dl_debug_bindings): Pass new hash value and reference to variable
	with the old value to do_lookup_x.
	* elf/do-lookup.h (do_lookup_x): Accept additional parameter with
	new-style hash value and change old-style hash value parameter to
	be a reference.  Reoganize functions to determine whether
	new-style hash table is available.  Only fall back on old-style
	table.  If old-style hash value is needed, compute it here.
	* elf/dynamic-link.h (elf_get_dynamic_info): Relocate DT_GNU_HASH
	entry.
	* elf/elf.h: Define SHT_GNU_HASH, DT_GNU_HASH, DT_TLSDEC_PLT,
	DT_TLSDEC_GOT.  Adjust DT_ADDRNUM.
	* include/link.h (struct link_map): Add l_gnu_bitmask_idxbits,
	l_gnu_shift, l_gnu_bitmask, l_gnu_buckets and l_gnu_chain_zero.
	* Makeconfig: If linker supports --hash-style option add it to all
	linker command lines to build DSOs.
	* config.make.in: Define have-hash-style.
	* configure.in: Test whether linker supports --hash-style option.

	* elf/dl-misc.c (_dl_name_match_p): Make MAP parameter const.
	* sysdeps/generic/ldsodefs.h: Adjust prototype.

1 files changed, 150 insertions, 108 deletions

diff --git a/elf/do-lookup.h b/elf/do-lookup.h
index 7b62b0feec..f40ab9d8d4 100644
--- a/elf/do-lookup.h
+++ b/elf/do-lookup.h
@@ -17,32 +17,29 @@
    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    02111-1307 USA.  */
 
+
 /* Inner part of the lookup functions.  We return a value > 0 if we
    found the symbol, the value 0 if nothing is found and < 0 if
    something bad happened.  */
 static int
 __attribute_noinline__
-do_lookup_x (const char *undef_name, unsigned long int hash,
-	     const ElfW(Sym) *ref, struct sym_val *result,
-	     struct r_scope_elem *scope, size_t i,
+do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
+	     unsigned long int *old_hash, const ElfW(Sym) *ref,
+	     struct sym_val *result, struct r_scope_elem *scope, size_t i,
 	     const struct r_found_version *const version, int flags,
 	     struct link_map *skip, int type_class)
 {
   struct link_map **list = scope->r_list;
   size_t n = scope->r_nlist;
-  struct link_map *map;
 
   do
     {
-      const ElfW(Sym) *symtab;
-      const char *strtab;
-      const ElfW(Half) *verstab;
+      /* These variables are used in the nested function.  */
       Elf_Symndx symidx;
-      const ElfW(Sym) *sym;
       int num_versions = 0;
       const ElfW(Sym) *versioned_sym = NULL;
 
-      map = list[i]->l_real;
+      const struct link_map *map = list[i]->l_real;
 
       /* Here come the extra test needed for `_dl_lookup_symbol_skip'.  */
       if (map == skip)
@@ -63,109 +60,158 @@ do_lookup_x (const char *undef_name, unsigned long int hash,
 			  map->l_name[0] ? map->l_name : rtld_progname,
 			  map->l_ns);
 
-      symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]);
-      strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
-      verstab = map->l_versyms;
+      /* If the hash table is empty there is nothing to do here.  */
+      if (map->l_nbuckets == 0)
+	continue;
 
-      /* Search the appropriate hash bucket in this object's symbol table
-	 for a definition for the same symbol name.  */
-      for (symidx = map->l_buckets[hash % map->l_nbuckets];
-	   symidx != STN_UNDEF;
-	   symidx = map->l_chain[symidx])
-	{
-	  sym = &symtab[symidx];
-
-	  assert (ELF_RTYPE_CLASS_PLT == 1);
-	  if ((sym->st_value == 0 /* No value.  */
-#ifdef USE_TLS
-	       && ELFW(ST_TYPE) (sym->st_info) != STT_TLS
-#endif
-	       )
-	      || (type_class & (sym->st_shndx == SHN_UNDEF)))
-	    continue;
-
-	  if (ELFW(ST_TYPE) (sym->st_info) > STT_FUNC
-#ifdef USE_TLS
-	      && ELFW(ST_TYPE) (sym->st_info) != STT_TLS
-#endif
-	      )
-	    /* Ignore all but STT_NOTYPE, STT_OBJECT and STT_FUNC
-	       entries (and STT_TLS if TLS is supported) since these
-	       are no code/data definitions.  */
-	    continue;
-
-	  if (sym != ref && strcmp (strtab + sym->st_name, undef_name))
-	    /* Not the symbol we are looking for.  */
-	    continue;
-
-	  if (version != NULL)
-	    {
-	      if (__builtin_expect (verstab == NULL, 0))
-		{
-		  /* We need a versioned symbol but haven't found any.  If
-		     this is the object which is referenced in the verneed
-		     entry it is a bug in the library since a symbol must
-		     not simply disappear.
-
-		     It would also be a bug in the object since it means that
-		     the list of required versions is incomplete and so the
-		     tests in dl-version.c haven't found a problem.*/
-		  assert (version->filename == NULL
-			  || ! _dl_name_match_p (version->filename, map));
-
-		  /* Otherwise we accept the symbol.  */
-		}
-	      else
-		{
-		  /* We can match the version information or use the
-		     default one if it is not hidden.  */
-		  ElfW(Half) ndx = verstab[symidx] & 0x7fff;
-		  if ((map->l_versions[ndx].hash != version->hash
-		       || strcmp (map->l_versions[ndx].name, version->name))
-		      && (version->hidden || map->l_versions[ndx].hash
-			  || (verstab[symidx] & 0x8000)))
-		    /* It's not the version we want.  */
-		    continue;
-		}
-	    }
-	  else
-	    {
-	      /* No specific version is selected.  There are two ways we
-		 can got here:
+      /* The tables for this map.  */
+      const ElfW(Sym) *symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]);
+      const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
+
+
+      /* Nested routine to check whether the symbol matches.  */
+      const ElfW(Sym) *
+      __attribute_noinline__
+      check_match (const ElfW(Sym) *sym)
+      {
+	assert (ELF_RTYPE_CLASS_PLT == 1);
+	if (__builtin_expect ((sym->st_value == 0 /* No value.  */
+			       && ELFW(ST_TYPE) (sym->st_info) != STT_TLS)
+			      || (type_class & (sym->st_shndx == SHN_UNDEF)),
+			      0))
+	  return NULL;
+
+	if (__builtin_expect (ELFW(ST_TYPE) (sym->st_info) > STT_FUNC
+			      && ELFW(ST_TYPE) (sym->st_info) != STT_TLS, 0))
+	  /* Ignore all but STT_NOTYPE, STT_OBJECT and STT_FUNC
+	     entries (and STT_TLS if TLS is supported) since these
+	     are no code/data definitions.  */
+	  return NULL;
+
+	if (sym != ref && strcmp (strtab + sym->st_name, undef_name))
+	  /* Not the symbol we are looking for.  */
+	  return NULL;
+
+	const ElfW(Half) *verstab = map->l_versyms;
+	if (version != NULL)
+	  {
+	    if (__builtin_expect (verstab == NULL, 0))
+	      {
+		/* We need a versioned symbol but haven't found any.  If
+		   this is the object which is referenced in the verneed
+		   entry it is a bug in the library since a symbol must
+		   not simply disappear.
+
+		   It would also be a bug in the object since it means that
+		   the list of required versions is incomplete and so the
+		   tests in dl-version.c haven't found a problem.*/
+		assert (version->filename == NULL
+			|| ! _dl_name_match_p (version->filename, map));
 
-		 - a binary which does not include versioning information
-		   is loaded
+		/* Otherwise we accept the symbol.  */
+	      }
+	    else
+	      {
+		/* We can match the version information or use the
+		   default one if it is not hidden.  */
+		ElfW(Half) ndx = verstab[symidx] & 0x7fff;
+		if ((map->l_versions[ndx].hash != version->hash
+		     || strcmp (map->l_versions[ndx].name, version->name))
+		    && (version->hidden || map->l_versions[ndx].hash
+			|| (verstab[symidx] & 0x8000)))
+		  /* It's not the version we want.  */
+		  return NULL;
+	      }
+	  }
+	else
+	  {
+	    /* No specific version is selected.  There are two ways we
+	       can got here:
 
-		 - dlsym() instead of dlvsym() is used to get a symbol which
-		   might exist in more than one form
+	       - a binary which does not include versioning information
+	       is loaded
 
-		 If the library does not provide symbol version
-		 information there is no problem at at: we simply use the
-		 symbol if it is defined.
+	       - dlsym() instead of dlvsym() is used to get a symbol which
+	       might exist in more than one form
 
-		 These two lookups need to be handled differently if the
-		 library defines versions.  In the case of the old
-		 unversioned application the oldest (default) version
-		 should be used.  In case of a dlsym() call the latest and
-		 public interface should be returned.  */
-	      if (verstab != NULL)
+	       If the library does not provide symbol version information
+	       there is no problem at at: we simply use the symbol if it
+	       is defined.
+
+	       These two lookups need to be handled differently if the
+	       library defines versions.  In the case of the old
+	       unversioned application the oldest (default) version
+	       should be used.  In case of a dlsym() call the latest and
+	       public interface should be returned.  */
+	    if (verstab != NULL)
+	      {
+		if ((verstab[symidx] & 0x7fff)
+		    >= ((flags & DL_LOOKUP_RETURN_NEWEST) ? 2 : 3))
+		  {
+		    /* Don't accept hidden symbols.  */
+		    if ((verstab[symidx] & 0x8000) == 0
+			&& num_versions++ == 0)
+		      /* No version so far.  */
+		      versioned_sym = sym;
+
+		    return NULL;
+		  }
+	      }
+	  }
+
+	/* There cannot be another entry for this symbol so stop here.  */
+	return sym;
+      }
+
+      const ElfW(Sym) *sym;
+      const ElfW(Addr) *bitmask = map->l_gnu_bitmask;
+      if (__builtin_expect (bitmask != NULL, 1))
+	{
+	  ElfW(Addr) bitmask_word
+	    = bitmask[(new_hash / __ELF_NATIVE_CLASS)
+		      & map->l_gnu_bitmask_idxbits];
+
+	  unsigned int hashbit1 = new_hash & (__ELF_NATIVE_CLASS - 1);
+	  unsigned int hashbit2 = ((new_hash >> map->l_gnu_shift)
+				   & (__ELF_NATIVE_CLASS - 1));
+
+	  if (__builtin_expect ((bitmask_word >> hashbit1)
+				& (bitmask_word >> hashbit2) & 1, 0))
+	    {
+	      Elf32_Word bucket = map->l_gnu_buckets[new_hash
+						     % map->l_nbuckets];
+	      if (bucket != 0)
 		{
-		  if ((verstab[symidx] & 0x7fff)
-		      >= ((flags & DL_LOOKUP_RETURN_NEWEST) ? 2 : 3))
-		    {
-		      /* Don't accept hidden symbols.  */
-		      if ((verstab[symidx] & 0x8000) == 0
-			  && num_versions++ == 0)
-			/* No version so far.  */
-			versioned_sym = sym;
+		  const Elf32_Word *hasharr = &map->l_gnu_chain_zero[bucket];
 
-		      continue;
-		    }
+		  do
+		    if ((*hasharr & ~1u) == (new_hash & ~1u))
+		      {
+			symidx = hasharr - map->l_gnu_chain_zero;
+			sym = check_match (&symtab[symidx]);
+			if (sym != NULL)
+			  goto found_it;
+		      }
+		  while ((*hasharr++ & 1u) == 0);
 		}
 	    }
+	}
+      else
+	{
+	  if (*old_hash == 0xffffffff)
+	    *old_hash = _dl_elf_hash (undef_name);
 
-	  /* There cannot be another entry for this symbol so stop here.  */
-	  goto found_it;
+	  /* Use the old SysV-style hash table.  Search the appropriate
+	     hash bucket in this object's symbol table for a definition
+	     for the same symbol name.  */
+	  for (symidx = map->l_buckets[*old_hash % map->l_nbuckets];
+	       symidx != STN_UNDEF;
+	       symidx = map->l_chain[symidx])
+	    {
+	      sym = check_match (&symtab[symidx]);
+	      if (sym != NULL)
+		goto found_it;
+	    }
 	}
 
       /* If we have seen exactly one versioned symbol while we are
@@ -186,7 +232,7 @@ do_lookup_x (const char *undef_name, unsigned long int hash,
 		  if (! result->s)
 		    {
 		      result->s = sym;
-		      result->m = map;
+		      result->m = (struct link_map *) map;
 		    }
 		  break;
 		}
@@ -194,7 +240,7 @@ do_lookup_x (const char *undef_name, unsigned long int hash,
 	    case STB_GLOBAL:
 	      /* Global definition.  Just what we need.  */
 	      result->s = sym;
-	      result->m = map;
+	      result->m = (struct link_map *) map;
 	      return 1;
 	    default:
 	      /* Local symbols are ignored.  */
@@ -213,7 +259,3 @@ do_lookup_x (const char *undef_name, unsigned long int hash,
   /* We have not found anything until now.  */
   return 0;
 }
-
-#undef FCT
-#undef ARG
-#undef VERSIONED