Re: [RFC PATCH] avoid intermingling executable and nonexecutable sections in a segment

[Roland McGrath <mcgrathr at google dot com>]

On Tue, Nov 20, 2012 at 3:01 PM, Alan Modra <amodra@gmail.com> wrote:
> Seems like you could do this much easier with a change to
> ldlang_override_segment_assignment controlled by a new global set from
> $SEPARATE_CODE.

OK, that's arguably much less kludgey.  I'm not clear on where a less
kludgey place to set that global might be.  How's this?


Thanks,
Roland


ld/
2012-11-20  Roland McGrath  <mcgrathr@google.com>

	* ldlang.c (lang_segments_separate_code): New global variable.
	(ldlang_override_segment_assignment): If that's true, then
	always return TRUE when SEC_CODE differs between the sections.
	* ldlang.h (lang_segments_separate_code): Declare it.
	* emultempl/elf32.em
	(gld${EMULATION_NAME}_after_open) [$SEPARATE_CODE = yes]: Set it.

--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -1061,6 +1061,14 @@ gld${EMULATION_NAME}_after_open (void)
   struct elf_link_hash_table *htab;

   after_open_default ();
+EOF
+if [ "x${SEPARATE_CODE}" = xyes ] ; then
+fragment <<EOF
+
+  lang_segments_separate_code = TRUE;
+EOF
+fi
+fragment <<EOF

   htab = elf_hash_table (&link_info);
   if (!is_elf_hash_table (htab))
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -113,6 +113,8 @@ struct lang_nocrossrefs *nocrossref_list;
     DEFINED() need to increment this.  */
 int lang_statement_iteration = 0;

+bfd_boolean lang_segments_separate_code = FALSE;
+
 etree_type *base; /* Relocation base - or null */

 /* Return TRUE if the PATTERN argument is a wildcard pattern.
@@ -5361,6 +5363,12 @@ ldlang_override_segment_assignment (struct
bfd_link_info * info ATTRIBUTE_UNUSED
   if (current_section == NULL || previous_section == NULL)
     return new_segment;

+  /* If this flag is set, the target never wants code and non-code
+     sections comingled in the same segment.  */
+  if (lang_segments_separate_code
+      && ((current_section->flags ^ previous_section->flags) & SEC_CODE))
+    return TRUE;
+
   /* Find the memory regions associated with the two sections.
      We call lang_output_section_find() here rather than scanning the list
      of output sections looking for a matching section pointer because if
--- a/ld/ldlang.h
+++ b/ld/ldlang.h
@@ -487,6 +487,8 @@ extern lang_statement_list_type input_file_chain;

 extern int lang_statement_iteration;

+extern bfd_boolean lang_segments_separate_code;
+
 extern void lang_init
   (void);
 extern void lang_finish