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PATCH: Add PROVIDE_HIDDEN

H. J. Lu hjl@lucon.org
Thu Aug 4 18:58:00 GMT 2005 
On Thu, Aug 04, 2005 at 10:41:24AM -0700, H. J. Lu wrote:
> On Thu, Aug 04, 2005 at 03:50:37PM +0930, Alan Modra wrote:
> > Now that we have stripping of empty output sections, even when they
> > contain symbols, a lot of special purpose code can be removed.  Simply
> > defining symbols in the linker script should work.  This patch does
> > that and also fixes some cases where PowerPC SDA relocs were
> > mishandled.
> > 
> 
> There is one problem. The linker provided symbols used to hidden, now
> they are global. It is a very bad when some bound symbols have to
> be provided for DSOs. I should we should make all linker provided
> symbol hidden for ELF.
> 
> 

This patch adds PROVIDE_HIDDEN.


H.J.
-------------- next part --------------
bfd/

2005-08-04  H.J. Lu  <hongjiu.lu@intel.com>

	* bfd.c (bfd_hide_symbol): New.
	* bfd-in2.h: Regenerated.

ld/

2005-08-04  H.J. Lu  <hongjiu.lu@intel.com>

	* ld.texinfo: Document PROVIDE_HIDDEN.

	* ldexp.c (exp_fold_tree_1): Hide a provided symbol if asked.
	(exp_provide): Add and set hidden.

	* ldexp.h (etree_type): Add hidden to assign.

	* ldgram.y (PROVIDE_HIDDEN): New.
	* ldlex.l (PROVIDE_HIDDEN): Likewise.

	* scripttempl/elf.sc: Use PROVIDE_HIDDEN on array bound
	symbols.

--- binutils/bfd/bfd.c.hidden	2005-06-06 08:54:38.000000000 -0700
+++ binutils/bfd/bfd.c	2005-08-04 11:32:16.211121884 -0700
@@ -1508,3 +1508,29 @@ bfd_preserve_finish (bfd *abfd ATTRIBUTE
      objalloc.  */
   bfd_hash_table_free (&preserve->section_htab);
 }
+
+/*
+FUNCTION
+	bfd_hide_symbol
+
+SYNOPSIS
+	void bfd_hide_symbol (bfd *,
+			      struct bfd_link_info *,
+			      struct bfd_link_hash_entry *,
+			      bfd_boolean);
+
+DESCRIPTION
+	This function hides a symbol so that it won't be exported. 
+
+*/
+
+void
+bfd_hide_symbol (bfd *abfd,
+		 struct bfd_link_info *link_info,
+		 struct bfd_link_hash_entry *h,
+		 bfd_boolean force_local)
+{
+  if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
+    (get_elf_backend_data (abfd)->elf_backend_hide_symbol)
+      (link_info, (struct elf_link_hash_entry *) h, force_local);
+}
--- binutils/ld/ldexp.c.hidden	2005-06-09 09:14:32.000000000 -0700
+++ binutils/ld/ldexp.c	2005-08-04 11:34:54.774025359 -0700
@@ -740,6 +740,8 @@ exp_fold_tree_1 (etree_type *tree)
 		     defined by some object.  */
 		  break;
 		}
+	      if (tree->assign.hidden)
+		bfd_hide_symbol (output_bfd, &link_info, h, TRUE);
 	    }
 
 	  exp_fold_tree_1 (tree->assign.src);
@@ -884,7 +886,7 @@ exp_assop (int code, const char *dst, et
 /* Handle PROVIDE.  */
 
 etree_type *
-exp_provide (const char *dst, etree_type *src)
+exp_provide (const char *dst, etree_type *src, bfd_boolean hidden)
 {
   etree_type *n;
 
@@ -893,6 +895,7 @@ exp_provide (const char *dst, etree_type
   n->assign.type.node_class = etree_provide;
   n->assign.src = src;
   n->assign.dst = dst;
+  n->assign.hidden = hidden;
   return n;
 }
 
--- binutils/ld/ldexp.h.hidden	2005-06-09 09:14:32.000000000 -0700
+++ binutils/ld/ldexp.h	2005-08-04 11:16:03.433223155 -0700
@@ -63,6 +63,7 @@ typedef union etree_union {
     node_type type;
     const char *dst;
     union etree_union *src;
+    bfd_boolean hidden;
   } assign;
   struct {
     node_type type;
@@ -165,7 +166,7 @@ etree_type *exp_nameop
 etree_type *exp_assop
   (int, const char *, etree_type *);
 etree_type *exp_provide
-  (const char *, etree_type *);
+  (const char *, etree_type *, bfd_boolean);
 etree_type *exp_assert
   (etree_type *, const char *);
 void exp_print_tree
--- binutils/ld/ldgram.y.hidden	2005-07-24 19:31:17.000000000 -0700
+++ binutils/ld/ldgram.y	2005-08-04 11:14:04.519794108 -0700
@@ -142,7 +142,7 @@ static int error_index;
 %token STARTUP HLL SYSLIB FLOAT NOFLOAT NOCROSSREFS
 %token ORIGIN FILL
 %token LENGTH CREATE_OBJECT_SYMBOLS INPUT GROUP OUTPUT CONSTRUCTORS
-%token ALIGNMOD AT SUBALIGN PROVIDE AS_NEEDED
+%token ALIGNMOD AT SUBALIGN PROVIDE PROVIDE_HIDDEN AS_NEEDED
 %type <token> assign_op atype attributes_opt sect_constraint
 %type <name>  filename
 %token CHIP LIST SECT ABSOLUTE  LOAD NEWLINE ENDWORD ORDER NAMEWORD ASSERT_K
@@ -648,7 +648,11 @@ assignment:
 		}
 	|	PROVIDE '(' NAME '=' mustbe_exp ')'
 		{
-		  lang_add_assignment (exp_provide ($3, $5));
+		  lang_add_assignment (exp_provide ($3, $5, FALSE));
+		}
+	|	PROVIDE_HIDDEN '(' NAME '=' mustbe_exp ')'
+		{
+		  lang_add_assignment (exp_provide ($3, $5, TRUE));
 		}
 	;
 
--- binutils/ld/ldlex.l.hidden	2005-05-16 11:04:40.000000000 -0700
+++ binutils/ld/ldlex.l	2005-08-04 11:34:11.716111896 -0700
@@ -313,6 +313,7 @@ V_IDENTIFIER [*?.$_a-zA-Z\[\]\-\!\^\\]([
 <EXPRESSION,BOTH,SCRIPT>"AT"		{ RTOKEN(AT);}
 <EXPRESSION,BOTH,SCRIPT>"SUBALIGN"	{ RTOKEN(SUBALIGN);}
 <EXPRESSION,BOTH,SCRIPT>"PROVIDE"	{ RTOKEN(PROVIDE); }
+<EXPRESSION,BOTH,SCRIPT>"PROVIDE_HIDDEN" { RTOKEN(PROVIDE_HIDDEN); }
 <EXPRESSION,BOTH,SCRIPT>"KEEP"		{ RTOKEN(KEEP); }
 <EXPRESSION,BOTH,SCRIPT>"EXCLUDE_FILE"  { RTOKEN(EXCLUDE_FILE); }
 <MRI>"#".*\n?			{ ++ lineno; }
--- binutils/ld/scripttempl/elf.sc.hidden	2005-08-04 08:56:47.315617114 -0700
+++ binutils/ld/scripttempl/elf.sc	2005-08-04 11:37:29.415574217 -0700
@@ -384,21 +384,21 @@ cat <<EOF
 
   .preinit_array   ${RELOCATING-0} :
   {
-    ${RELOCATING+${CREATE_SHLIB-PROVIDE (__preinit_array_start = .);}}
+    ${RELOCATING+${CREATE_SHLIB-PROVIDE_HIDDEN (__preinit_array_start = .);}}
     KEEP (*(.preinit_array))
-    ${RELOCATING+${CREATE_SHLIB-PROVIDE (__preinit_array_end = .);}}
+    ${RELOCATING+${CREATE_SHLIB-PROVIDE_HIDDEN (__preinit_array_end = .);}}
   }
   .init_array   ${RELOCATING-0} :
   {
-     ${RELOCATING+${CREATE_SHLIB-PROVIDE (__init_array_start = .);}}
+     ${RELOCATING+${CREATE_SHLIB-PROVIDE_HIDDEN (__init_array_start = .);}}
      KEEP (*(.init_array))
-     ${RELOCATING+${CREATE_SHLIB-PROVIDE (__init_array_end = .);}}
+     ${RELOCATING+${CREATE_SHLIB-PROVIDE_HIDDEN (__init_array_end = .);}}
   }
   .fini_array   ${RELOCATING-0} :
   {
-    ${RELOCATING+${CREATE_SHLIB-PROVIDE (__fini_array_start = .);}}
+    ${RELOCATING+${CREATE_SHLIB-PROVIDE_HIDDEN (__fini_array_start = .);}}
     KEEP (*(.fini_array))
-    ${RELOCATING+${CREATE_SHLIB-PROVIDE (__fini_array_end = .);}}
+    ${RELOCATING+${CREATE_SHLIB-PROVIDE_HIDDEN (__fini_array_end = .);}}
   }
   ${SMALL_DATA_CTOR-${RELOCATING+${CTOR}}}
   ${SMALL_DATA_DTOR-${RELOCATING+${DTOR}}}
--- binutils/ld/ld.texinfo.hide	2005-08-04 11:40:55.181708913 -0700
+++ binutils/ld/ld.texinfo	2005-08-04 11:48:25.844839998 -0700
@@ -2781,6 +2781,7 @@ the symbol and place it into the symbol 
 @menu
 * Simple Assignments::		Simple Assignments
 * PROVIDE::			PROVIDE
+* PROVIDE_HIDDEN::		PROVIDE_HIDDEN
 * Source Code Reference::	How to use a linker script defined symbol in source code
 @end menu
 
@@ -2874,6 +2875,12 @@ underscore), the linker will silently us
 If the program references @samp{etext} but does not define it, the
 linker will use the definition in the linker script.
 
+@node PROVIDE_HIDDEN
+@subsection PROVIDE_HIDDEN
+@cindex PROVIDE_HIDDEN
+Similar to @code{PROVIDE}. But the symbol will be hidden and won't be
+exported.
+
 @node Source Code Reference
 @subsection Source Code Reference
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