* config/obj-elf.c (obj_elf_type): Add code to support a type of

        gnu_unique_object.
        * doc/as.texinfo: Document new feature of .type directive.
        * NEWS: Mention support for gnu_unique_object symbol type.

        * common.h (STB_GNU_UNIQUE): Define.

        * NEWS: Mention the linker's support for symbols with a binding of
        STB_GNU_UNIQUE.

        * gas/elf/type.s: Add unique global symbol definition.
        * gas/elf/type.e: Add expected readelf output for global unique
        symbol.

        * elfcpp.h (enum STB): Add STB_GNU_UNIQUE.

        * readelf.c (get_symbol_binding): For Linux targeted files return
        UNIQUE for symbols with the STB_GNU_UNIQUE binding.
        * doc/binutils.texi: Document the meaning of the 'u' symbol
        binding in the output of nm and objdump --syms.

        * elf-bfd.h (struct elf_link_hash_entry): Add unique_global field.
        * elf.c (swap_out_syms): Set binding to STB_GNU_UNIQUE for symbols
        with the BSF_GNU_UNIQUE flag bit set.
        * elfcode.h (elf_slurp_symbol_table): Set the BSF_GNU_UNIQUE flag
        for symbols with STB_GNU_UNIQUE binding.
        * elflink.c (_bfd_elf_merge_symbol): Set unique_global for symbols
        with the STB_GNU_UNIQUE binding.
        (elf_link_add_object_symbols): Set the BSF_GNU_UNIQUE flag for
        symbols with STB_GNU_UNIQUE binding.  Set STB_GNU_UNIQUE for
        symbols with the unique_global field set.
        (elf_link_output_extsym): Set unique_global field for symbols with
        the STB_GNU_UNIQUE binding.
        * syms.c (struct bfd_symbol): Define BSF_GNU_UNIQUE flag bit.
        (bfd_print_symbol_vandf): Print a 'u' character for BSF_GNU_UNIQUE
        symbols.
        (bfd_decode_symclass): Return a 'u' character for BSF_GNU_UNIQUE
        symbols.
        * bfd-in2.h: Regenerate.

23 files changed, 167 insertions, 18 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 7987bbc..42dd8e3 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,24 @@
+2009-07-23  Ulrich Drepper  <drepper@redhat.com>
+
+	* elf-bfd.h (struct elf_link_hash_entry): Add unique_global field.
+	* elf.c (swap_out_syms): Set binding to STB_GNU_UNIQUE for symbols
+	with the BSF_GNU_UNIQUE flag bit set.
+	* elfcode.h (elf_slurp_symbol_table): Set the BSF_GNU_UNIQUE flag
+	for symbols with STB_GNU_UNIQUE binding.
+	* elflink.c (_bfd_elf_merge_symbol): Set unique_global for symbols
+	with the STB_GNU_UNIQUE binding.
+	(elf_link_add_object_symbols): Set the BSF_GNU_UNIQUE flag for
+	symbols with STB_GNU_UNIQUE binding.  Set STB_GNU_UNIQUE for
+	symbols with the unique_global field set.
+	(elf_link_output_extsym): Set unique_global field for symbols with
+	the STB_GNU_UNIQUE binding.
+	* syms.c (struct bfd_symbol): Define BSF_GNU_UNIQUE flag bit.
+	(bfd_print_symbol_vandf): Print a 'u' character for BSF_GNU_UNIQUE
+	symbols.
+	(bfd_decode_symclass): Return a 'u' character for BSF_GNU_UNIQUE
+	symbols.
+	* bfd-in2.h: Regenerate.
+
 2009-07-22  H.J. Lu  <hongjiu.lu@intel.com>
 
 	 * elflink.c (elf_link_output_extsym): Revert the last change.
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 5244b9a..562f833 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -4639,6 +4639,10 @@ typedef struct bfd_symbol
      calling the function that it points to.  BSF_FUNCTION must
      also be also set.  */
 #define BSF_GNU_INDIRECT_FUNCTION (1 << 22)
+  /* This symbol is a globally unique data object.  The dynamic linker
+     will make sure that in the entire process there is just one symbol
+     with this name and type in use.  BSF_OBJECT must also be set.  */
+#define BSF_GNU_UNIQUE         (1 << 23)
 
   flagword flags;
 
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index 1690def..8f70d79 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -178,6 +178,8 @@ struct elf_link_hash_entry
   /* Symbol is referenced with a relocation where C/C++ pointer equality
      matters.  */
   unsigned int pointer_equality_needed : 1;
+  /* Symbol is a unique global symbol.  */
+  unsigned int unique_global : 1;
 
   /* String table index in .dynstr if this is a dynamic symbol.  */
   unsigned long dynstr_index;
diff --git a/bfd/elf.c b/bfd/elf.c
index 19f2684..f27c607 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -6446,6 +6446,8 @@ Unable to find equivalent output section for symbol '%s' from section '%s'"),
 
 	  if (flags & BSF_LOCAL)
 	    bind = STB_LOCAL;
+	  else if (flags & BSF_GNU_UNIQUE)
+	    bind = STB_GNU_UNIQUE;
 	  else if (flags & BSF_WEAK)
 	    bind = STB_WEAK;
 	  else if (flags & BSF_GLOBAL)
diff --git a/bfd/elfcode.h b/bfd/elfcode.h
index 024ead4..10aa131 100644
--- a/bfd/elfcode.h
+++ b/bfd/elfcode.h
@@ -1,6 +1,6 @@
 /* ELF executable support for BFD.
    Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
-   2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+   2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
    Free Software Foundation, Inc.
 
    Written by Fred Fish @ Cygnus Support, from information published
@@ -1282,6 +1282,9 @@ elf_slurp_symbol_table (bfd *abfd, asymbol **symptrs, bfd_boolean dynamic)
 	    case STB_WEAK:
 	      sym->symbol.flags |= BSF_WEAK;
 	      break;
+	    case STB_GNU_UNIQUE:
+	      sym->symbol.flags |= BSF_GNU_UNIQUE;
+	      break;
 	    }
 
 	  switch (ELF_ST_TYPE (isym->st_info))
diff --git a/bfd/elflink.c b/bfd/elflink.c
index f9b577c..a117063 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -1248,6 +1248,9 @@ _bfd_elf_merge_symbol (bfd *abfd,
   oldweak = (h->root.type == bfd_link_hash_defweak
 	     || h->root.type == bfd_link_hash_undefweak);
 
+  if (bind == STB_GNU_UNIQUE)
+    h->unique_global = 1;
+
   /* If a new weak symbol definition comes from a regular file and the
      old symbol comes from a dynamic library, we treat the new one as
      strong.  Similarly, an old weak symbol definition from a regular
@@ -3871,24 +3874,31 @@ error_free_dyn:
       common = bed->common_definition (isym);
 
       bind = ELF_ST_BIND (isym->st_info);
-      if (bind == STB_LOCAL)
+      switch (bind)
 	{
+	case STB_LOCAL:
 	  /* This should be impossible, since ELF requires that all
 	     global symbols follow all local symbols, and that sh_info
 	     point to the first global symbol.  Unfortunately, Irix 5
 	     screws this up.  */
 	  continue;
-	}
-      else if (bind == STB_GLOBAL)
-	{
+
+	case STB_GLOBAL:
 	  if (isym->st_shndx != SHN_UNDEF && !common)
 	    flags = BSF_GLOBAL;
-	}
-      else if (bind == STB_WEAK)
-	flags = BSF_WEAK;
-      else
-	{
+	  break;
+
+	case STB_WEAK:
+	  flags = BSF_WEAK;
+	  break;
+
+	case STB_GNU_UNIQUE:
+	  flags = BSF_GNU_UNIQUE;
+	  break;
+
+	default:
 	  /* Leave it up to the processor backend.  */
+	  break;
 	}
 
       if (isym->st_shndx == SHN_UNDEF)
@@ -4140,7 +4150,9 @@ error_free_dyn:
       while (h->root.type == bfd_link_hash_indirect
 	     || h->root.type == bfd_link_hash_warning)
 	h = (struct elf_link_hash_entry *) h->root.u.i.link;
+
       *sym_hash = h;
+      h->unique_global = (flags & BSF_GNU_UNIQUE) != 0;
 
       new_weakdef = FALSE;
       if (dynamic
@@ -8571,6 +8583,8 @@ elf_link_output_extsym (struct elf_link_hash_entry *h, void *data)
   sym.st_other = h->other;
   if (h->forced_local)
     sym.st_info = ELF_ST_INFO (STB_LOCAL, h->type);
+  else if (h->unique_global)
+    sym.st_info = ELF_ST_INFO (STB_GNU_UNIQUE, h->type);
   else if (h->root.type == bfd_link_hash_undefweak
 	   || h->root.type == bfd_link_hash_defweak)
     sym.st_info = ELF_ST_INFO (STB_WEAK, h->type);
diff --git a/bfd/syms.c b/bfd/syms.c
index 6abb929..e4258b5 100644
--- a/bfd/syms.c
+++ b/bfd/syms.c
@@ -302,6 +302,10 @@ CODE_FRAGMENT
 .     calling the function that it points to.  BSF_FUNCTION must
 .     also be also set.  *}
 .#define BSF_GNU_INDIRECT_FUNCTION (1 << 22)
+.  {* This symbol is a globally unique data object.  The dynamic linker
+.     will make sure that in the entire process there is just one symbol
+.     with this name and type in use.  BSF_OBJECT must also be set.  *}
+.#define BSF_GNU_UNIQUE		(1 << 23)
 .
 .  flagword flags;
 .
@@ -485,7 +489,8 @@ bfd_print_symbol_vandf (bfd *abfd, void *arg, asymbol *symbol)
   fprintf (file, " %c%c%c%c%c%c%c",
 	   ((type & BSF_LOCAL)
 	    ? (type & BSF_GLOBAL) ? '!' : 'l'
-	    : (type & BSF_GLOBAL) ? 'g' : ' '),
+	    : (type & BSF_GLOBAL) ? 'g'
+	    : (type & BSF_GNU_UNIQUE) ? 'u' : ' '),
 	   (type & BSF_WEAK) ? 'w' : ' ',
 	   (type & BSF_CONSTRUCTOR) ? 'C' : ' ',
 	   (type & BSF_WARNING) ? 'W' : ' ',
@@ -686,6 +691,8 @@ bfd_decode_symclass (asymbol *symbol)
       else
 	return 'W';
     }
+  if (symbol->flags & BSF_GNU_UNIQUE)
+    return 'u';
   if (!(symbol->flags & (BSF_GLOBAL | BSF_LOCAL)))
     return '?';
 
diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index 89b1a66..28caa23 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,3 +1,10 @@
+2009-07-23  Ulrich Drepper  <drepper@redhat.com>
+
+	* readelf.c (get_symbol_binding): For Linux targeted files return
+	UNIQUE for symbols with the STB_GNU_UNIQUE binding.
+	* doc/binutils.texi: Document the meaning of the 'u' symbol
+	binding in the output of nm and objdump --syms.
+
 2009-07-20  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* NEWS: Mention --insn-width.
diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi
index 98438f2..a5856b2 100644
--- a/binutils/doc/binutils.texi
+++ b/binutils/doc/binutils.texi
@@ -745,7 +745,13 @@ object file formats permit more efficient access to small data objects,
 such as a global int variable as opposed to a large global array.
 
 @item i
-The symbol is in a section specific to the implementation of DLLs.
+For PE format files this indicates that the symbol is in a section
+specific to the implementation of DLLs.  For ELF format files this
+indicates that the symbol is an indirect function.  This is a GNU
+extension to the standard set of ELF symbol types.  It indicates a
+symbol which if referenced by a relocation does not evaluate to its
+address, but instead must be invoked at runtime.  The runtime
+execution will then return the value to be used in the relocation.
 
 @item N
 The symbol is a debugging symbol.
@@ -768,6 +774,12 @@ The symbol is in the text (code) section.
 @item U
 The symbol is undefined.
 
+@item u
+The symbol is a unique global symbol.  This is a GNU extension to the
+standard set of ELF symbol bindings.  For such a symbol the dynamic linker
+will make sure that in the entire process there is just one symbol with
+this name and type in use.
+
 @item V
 @itemx v
 The symbol is a weak object.  When a weak defined symbol is linked with
@@ -2142,11 +2154,16 @@ The flag characters are divided into 7 groups as follows:
 @table @code
 @item l
 @itemx g
+@itemx u
 @itemx !
-The symbol is local (l), global (g), neither (a space) or both (!).  A
+The symbol is a local (l), global (g), unique global (u), neither
+global nor local (a space) or both global and local (!).  A
 symbol can be neither local or global for a variety of reasons, e.g.,
 because it is used for debugging, but it is probably an indication of
-a bug if it is ever both local and global.
+a bug if it is ever both local and global.  Unique global symbols are
+a GNU extension to the standard set of ELF symbol bindings.  For such
+a symbol the dynamic linker will make sure that in the entire process
+there is just one symbol with this name and type in use.
 
 @item w
 The symbol is weak (w) or strong (a space).
diff --git a/binutils/readelf.c b/binutils/readelf.c
index ce739e6..f56e6c2 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -6902,7 +6902,14 @@ get_symbol_binding (unsigned int binding)
 	snprintf (buff, sizeof (buff), _("<processor specific>: %d"),
 		  binding);
       else if (binding >= STB_LOOS && binding <= STB_HIOS)
-	snprintf (buff, sizeof (buff), _("<OS specific>: %d"), binding);
+	{
+	  if (binding == STB_GNU_UNIQUE
+	      && (elf_header.e_ident[EI_OSABI] == ELFOSABI_LINUX
+		  /* GNU/Linux is still using the default value 0.  */
+		  || elf_header.e_ident[EI_OSABI] == ELFOSABI_NONE))
+	    return "UNIQUE";
+	  snprintf (buff, sizeof (buff), _("<OS specific>: %d"), binding);
+	}
       else
 	snprintf (buff, sizeof (buff), _("<unknown>: %d"), binding);
       return buff;
diff --git a/elfcpp/ChangeLog b/elfcpp/ChangeLog
index 2a8204f..2a668a6 100644
--- a/elfcpp/ChangeLog
+++ b/elfcpp/ChangeLog
@@ -1,3 +1,7 @@
+2009-07-23  Ulrich Drepper  <drepper@redhat.com>
+
+	* elfcpp.h (enum STB): Add STB_GNU_UNIQUE.
+
 2009-06-21  Ian Lance Taylor  <iant@google.com>
 
 	* elfcpp.h (SHN_X86_64_LCOMMON): Define enum constant.
diff --git a/elfcpp/elfcpp.h b/elfcpp/elfcpp.h
index 1b1a875..683cd9d 100644
--- a/elfcpp/elfcpp.h
+++ b/elfcpp/elfcpp.h
@@ -485,6 +485,7 @@ enum STB
   STB_GLOBAL = 1,
   STB_WEAK = 2,
   STB_LOOS = 10,
+  STB_GNU_UNIQUE = 10,
   STB_HIOS = 12,
   STB_LOPROC = 13,
   STB_HIPROC = 15
diff --git a/gas/ChangeLog b/gas/ChangeLog
index 8f150fc..de98024 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,10 @@
+2009-07-23  Ulrich Drepper  <drepper@redhat.com>
+
+	* config/obj-elf.c (obj_elf_type): Add code to support a type of
+	gnu_unique_object.
+	* doc/as.texinfo: Document new feature of .type directive.
+	* NEWS: Mention support for gnu_unique_object symbol type.
+
 2009-07-23  Nick Clifton  <nickc@redhat.com>
 
 	PR binutils/10379
diff --git a/gas/NEWS b/gas/NEWS
index 529f4ab..c2eea84 100644
--- a/gas/NEWS
+++ b/gas/NEWS
@@ -1,4 +1,8 @@
 -*- text -*-
+* GNU/Linux targets now supports "gnu_unique_object" as a value in the .type
+  pseudo op.  It marks the symbol as being globally unique in the entire
+  process.
+
 * ARM assembler now supports .inst[.nw] pseudo-ops to insert opcodes specified
   in binary rather than text.
 
diff --git a/gas/config/obj-elf.c b/gas/config/obj-elf.c
index 3c72326..c9c7a9c 100644
--- a/gas/config/obj-elf.c
+++ b/gas/config/obj-elf.c
@@ -1665,8 +1665,8 @@ obj_elf_type (int ignore ATTRIBUTE_UNUSED)
 	}
     }
   else if (strcmp (typename, "gnu_indirect_function") == 0
-      || strcmp (typename, "10") == 0
-      || strcmp (typename, "STT_GNU_IFUNC") == 0)
+	   || strcmp (typename, "10") == 0
+	   || strcmp (typename, "STT_GNU_IFUNC") == 0)
     {
       const struct elf_backend_data *bed;
 
@@ -1678,6 +1678,18 @@ obj_elf_type (int ignore ATTRIBUTE_UNUSED)
 		typename);
       type = BSF_FUNCTION | BSF_GNU_INDIRECT_FUNCTION;
     }
+  else if (strcmp (typename, "gnu_unique_object") == 0)
+    {
+      const struct elf_backend_data *bed;
+
+      bed = get_elf_backend_data (stdoutput);
+      if (!(bed->elf_osabi == ELFOSABI_LINUX
+	    /* GNU/Linux is still using the default value 0.  */
+	    || bed->elf_osabi == ELFOSABI_NONE))
+	as_bad (_("symbol type \"%s\" is supported only by GNU targets"),
+		typename);
+      type = BSF_OBJECT | BSF_GNU_UNIQUE;
+    }
 #ifdef md_elf_symbol_type
   else if ((type = md_elf_symbol_type (typename, sym, elfsym)) != -1)
     ;
diff --git a/gas/doc/as.texinfo b/gas/doc/as.texinfo
index d1240bf..3af86f8 100644
--- a/gas/doc/as.texinfo
+++ b/gas/doc/as.texinfo
@@ -6360,6 +6360,11 @@ Mark the symbol as being a common data object.
 @itemx notype
 Does not mark the symbol in any way.  It is supported just for completeness.
 
+@item gnu_unique_object
+Marks the symbol as being a globally unique data object.  The dynamic linker
+will make sure that in the entire process there is just one symbol with this
+name and type in use.  (This is only supported on Linux targeted assemblers).
+
 @end table
 
 Note: Some targets support extra types in addition to those listed above.
diff --git a/gas/testsuite/ChangeLog b/gas/testsuite/ChangeLog
index a5d0bdb..a30164b 100644
--- a/gas/testsuite/ChangeLog
+++ b/gas/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2009-07-23  Ulrich Drepper  <drepper@redhat.com>
+
+	* gas/elf/type.s: Add unique global symbol definition.
+	* gas/elf/type.e: Add expected readelf output for global unique
+	symbol.
+
 2009-07-21  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR gas/10420
diff --git a/gas/testsuite/gas/elf/type.e b/gas/testsuite/gas/elf/type.e
index 95d846a..2d26af8 100644
--- a/gas/testsuite/gas/elf/type.e
+++ b/gas/testsuite/gas/elf/type.e
@@ -3,4 +3,5 @@
      .: 0+0     1 OBJECT  LOCAL  DEFAULT    . object
      .: 0+1     1 TLS     LOCAL  DEFAULT    . tls_object
     ..: 0+2     1 NOTYPE  LOCAL  DEFAULT    . notype
+    ..: 0+3     1 OBJECT  UNIQUE DEFAULT    . unique_global
     ..: 0+1     1 (COMMON|OBJECT)  GLOBAL DEFAULT  COM common
diff --git a/gas/testsuite/gas/elf/type.s b/gas/testsuite/gas/elf/type.s
index 8620cc2..159bf6d 100644
--- a/gas/testsuite/gas/elf/type.s
+++ b/gas/testsuite/gas/elf/type.s
@@ -1,24 +1,35 @@
 	.text
+	
         .size   function,1
         .type   function,%function
 function:
 	.byte	0x0
+	
         .size   indirect_function,1
         .type   indirect_function,%gnu_indirect_function
 indirect_function:
 	.byte	0x0
+	
         .data
+	
         .type   object,%object
         .size   object,1
 object:
 	.byte	0x0
         .type   tls_object,%tls_object
+	
         .size   tls_object,1
 tls_object:
 	.byte	0x0
         .type   notype,%notype
+	
         .size   notype,1
 notype:
 	.byte	0x0
 	.comm	common, 1
 	.type   common,STT_COMMON
+
+	.type	unique_global,%gnu_unique_object
+unique_global:
+	.byte	0x0
+	.size	unique_global,1
diff --git a/include/elf/ChangeLog b/include/elf/ChangeLog
index 89235d1..600342c 100644
--- a/include/elf/ChangeLog
+++ b/include/elf/ChangeLog
@@ -1,3 +1,7 @@
+2009-07-23  Ulrich Drepper  <drepper@redhat.com>
+
+	* common.h (STB_GNU_UNIQUE): Define.
+
 2009-07-10  Tom Tromey  <tromey@redhat.com>
 
 	* dwarf2.h: Move to `..'.
diff --git a/include/elf/common.h b/include/elf/common.h
index 75f4eb8..72afa91 100644
--- a/include/elf/common.h
+++ b/include/elf/common.h
@@ -1,6 +1,6 @@
 /* ELF support for BFD.
    Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
-   2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+   2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
    Free Software Foundation, Inc.
 
    Written by Fred Fish @ Cygnus Support, from information published
@@ -555,6 +555,7 @@
 #define STB_GLOBAL	1		/* Symbol visible outside obj */
 #define STB_WEAK	2		/* Like globals, lower precedence */
 #define STB_LOOS	10		/* OS-specific semantics */
+#define STB_GNU_UNIQUE	10		/* Symbol is unique in namespace */
 #define STB_HIOS	12		/* OS-specific semantics */
 #define STB_LOPROC	13		/* Processor-specific semantics */
 #define STB_HIPROC	15		/* Processor-specific semantics */
diff --git a/ld/ChangeLog b/ld/ChangeLog
index 87ab48b..10160eb 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,8 @@
+2009-07-23  Ulrich Drepper  <drepper@redhat.com>
+
+	* NEWS: Mention the linker's support for symbols with a binding of
+	STB_GNU_UNIQUE.
+
 2009-07-22  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR ld/10429
diff --git a/ld/NEWS b/ld/NEWS
index 6f05361..821915e 100644
--- a/ld/NEWS
+++ b/ld/NEWS
@@ -1,4 +1,8 @@
 -*- text -*-
+* GNU/Linux targets now support the STB_GNU_UNIQUE symbol binding.  This is a
+  GNU extension to the standard set of ELF symbol bindings.  The binding will
+  be passed on to the dynamic linker which will make sure that in the entire
+  process there is just one symbol with the given name and type in use.
 
 * PE targets now support a GNU extension to allow the alignment of common
   common symbols to be specified.  This support uses custom options in