[binutils-gdb] OAv2 merge: create a section for object attributes

[Matthieu Longo]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=0ea2dc5006a8d57065f04fe63350cb0db8aa769e

commit 0ea2dc5006a8d57065f04fe63350cb0db8aa769e
Author: Matthieu Longo <matthieu.longo@arm.com>
Date:   Fri Nov 14 18:44:46 2025 +0000

    OAv2 merge: create a section for object attributes
    
    bfd copies object attributes to the output BFD only if the input BFD —
    used to store the merge result— contains an object attribute section.
    bfd_linear_find_first_with_obj_attrs() returns an input BFD that may or
    may not already include such a section.  If no object attributes section
    is found, the merge process must create one.
    
    This patch implements create_object_attributes_section(), which constructs
    the missing section with the appropriate flags, type, and alignment.  The
    implementation is adapted from _bfd_elf_link_create_gnu_property_sec() in
    bfd/elf-properties.c.  The code preserves the different alignment
    requirements for 32-bit and 64-bit ELF formats, although the rationale for
    this distinction remains unclear in the original source and patch history.

Diff:
---
 bfd/elf-attrs.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/bfd/elf-attrs.c b/bfd/elf-attrs.c
index b9b8abd5017..4b943376016 100644
--- a/bfd/elf-attrs.c
+++ b/bfd/elf-attrs.c
@@ -796,10 +796,24 @@ static asection *
 create_object_attributes_section (struct bfd_link_info *info,
 				  bfd *abfd)
 {
-  (void) info;
-  (void) abfd;
-  /* TO IMPLEMENT */
-  return NULL;
+  asection *sec;
+  const char *sec_name = get_elf_backend_data (abfd)->obj_attrs_section;
+  sec = bfd_make_section_with_flags (abfd,
+				     sec_name,
+				     (SEC_READONLY
+				      | SEC_HAS_CONTENTS
+				      | SEC_DATA));
+  if (sec == NULL)
+    info->callbacks->fatal (_("%P: failed to create %s section\n"), sec_name);
+
+  if (!bfd_set_section_alignment (sec, 2))
+    info->callbacks->fatal (_("%pA: failed to align section\n"), sec);
+
+  elf_section_type (sec) = get_elf_backend_data (abfd)->obj_attrs_section_type;
+
+  bfd_set_section_size (sec, bfd_elf_obj_attr_size (abfd));
+
+  return sec;
 }
 
 /* Translate GNU properties that have object attributes v2 equivalents.  */