linking elf notes together on elf32-arm

linking elf notes together on elf32-arm

[Mark Wielaard]

Hi,

While trying to build a program that uses sdt elf notes on an elf32-arm
architecture I get the following error on the final link:
/usr/bin/ld: staprun-util.o: duplicate section `.note.stapsdt' has
different size

The different object files do have different sized note sections,
because they contain different things and so shouldn't be merged
together as duplicates.

This is because all elf notes are marked as link once in
bfd/elf32-arm.c:

/* Set the right machine number for an Arm ELF file.  */

static bfd_boolean
elf32_arm_section_flags (flags, hdr)
     flagword *flags;
     Elf_Internal_Shdr *hdr;
{
  if (hdr->sh_type == SHT_NOTE)
    *flags |= SEC_LINK_ONCE | SEC_LINK_DUPLICATES_SAME_CONTENTS;

  return TRUE;
}

That seems wrong to me. Why are all SHT_NOTE sections treated that way?
Should it be just some specific arm named ones?

It seems to have been introduced a long time ago:

2003-03-25  Stan Cox   <scox@redhat.com>
            Nick Clifton  <nickc@redhat.com>
           
   Contribute support for Intel's iWMMXt chip - an ARM variant:
[...]
   (elf32_arm_section_flags): New function: Set flags on note section.

Can anybody remember why that was, and how to make it so that "normal"
elf notes don't get merged?

Thanks,

Mark

Re: linking elf notes together on elf32-arm

[Nick Clifton]

Hi Mark,

> static bfd_boolean
> elf32_arm_section_flags (flags, hdr)
>       flagword *flags;
>       Elf_Internal_Shdr *hdr;
> {
>    if (hdr->sh_type == SHT_NOTE)
>      *flags |= SEC_LINK_ONCE | SEC_LINK_DUPLICATES_SAME_CONTENTS;

This is a snafu.  It is left over from some old code which used to store 
ARM attributes in a note section.  It is no longer needed, so I am going 
to check in the patch below to remove it.

Cheers
   Nick

bfd/ChangeLog
2011-07-12  Nick Clifton  <nickc@redhat.com>

	* elf32-arm.c (elf32_arm_section_flags): Delete.
	(elf_backend_section_flags): Remove.

Index: bfd/elf32-arm.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-arm.c,v
retrieving revision 1.272
diff -u -3 -p -r1.272 elf32-arm.c
--- bfd/elf32-arm.c	22 Jun 2011 16:06:00 -0000	1.272
+++ bfd/elf32-arm.c	12 Jul 2011 15:15:51 -0000
@@ -14101,17 +14101,6 @@ elf32_arm_reloc_type_class (const Elf_In
      }
  }

-/* Set the right machine number for an Arm ELF file.  */
-
-static bfd_boolean
-elf32_arm_section_flags (flagword *flags, const Elf_Internal_Shdr *hdr)
-{
-  if (hdr->sh_type == SHT_NOTE)
-    *flags |= SEC_LINK_ONCE | SEC_LINK_DUPLICATES_SAME_CONTENTS;
-
-  return TRUE;
-}
-
  static void
  elf32_arm_final_write_processing (bfd *abfd, bfd_boolean linker 
ATTRIBUTE_UNUSED)
  {
@@ -15337,7 +15326,6 @@ const struct elf_size_info elf32_arm_siz
  #define elf_backend_post_process_headers	elf32_arm_post_process_headers
  #define elf_backend_reloc_type_class		elf32_arm_reloc_type_class
  #define elf_backend_object_p			elf32_arm_object_p
-#define elf_backend_section_flags		elf32_arm_section_flags
  #define elf_backend_fake_sections  		elf32_arm_fake_sections
  #define elf_backend_section_from_shdr  		elf32_arm_section_from_shdr
  #define elf_backend_final_write_processing 
elf32_arm_final_write_processing