[binutils-gdb] elf: Clear the SEC_ALLOC bit for NOLOAD note sections

[H.J. Lu]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d87be451ebbf831d44ac168ca9ea2b79ab5a79b3

commit d87be451ebbf831d44ac168ca9ea2b79ab5a79b3
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Mar 13 11:52:00 2025 -0700

    elf: Clear the SEC_ALLOC bit for NOLOAD note sections
    
    When generating an ELF output file, if a note section is marked as
    NOLOAD, clear the SEC_ALLOC bit so that it won't be treated as an
    SHF_ALLOC section, like a .bss style section.
    
            PR ld/32787
            * ld.texi: Update NOLOAD for ELF output files.
            * ldlang.c (lang_add_section): Clear the SEC_ALLOC bit for NOLOAD
            note sections for ELF output files.
            * testsuite/ld-elf/pr32787.d: New file.
            * testsuite/ld-elf/pr32787.t: Likewise.
    
    Signed-off-by: H.J. Lu <hjl.tools@gmail.com>

Diff:
---
 ld/ld.texi                    |  8 +++++++-
 ld/ldlang.c                   |  6 ++++--
 ld/testsuite/ld-elf/pr32787.d |  9 +++++++++
 ld/testsuite/ld-elf/pr32787.t | 12 ++++++++++++
 4 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/ld/ld.texi b/ld/ld.texi
index 6d51ccbe572..b85d8103b9f 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -5965,7 +5965,13 @@ parentheses.  The following types are defined:
 
 @item NOLOAD
 The section should be marked as not loadable, so that it will not be
-loaded into memory when the program is run.
+loaded into memory when the program is run.  When generating an ELF
+output file, the memory space is allocated for the section at run-time,
+except for SHT_NOTE sections.  For other output files, no memory space
+is allocated at run-time.
+
+Note - the ELF behaviour is a bug that may change to be consistent
+with non-ELF targets.
 
 @item READONLY
 The section should be marked as read-only.
diff --git a/ld/ldlang.c b/ld/ldlang.c
index 011c5262f87..0048dfa4911 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -2827,8 +2827,10 @@ lang_add_section (lang_statement_list_type *ptr,
       /* Unfortunately GNU ld has managed to evolve two different
 	 meanings to NOLOAD in scripts.  ELF gets a .bss style noload,
 	 alloc, no contents section.  All others get a noload, noalloc
-	 section.  */
-      if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour)
+	 section.  Unlike a .bss style section, if a note section is
+	 marked as NOLOAD, also clear SEC_ALLOC.  */
+      if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour
+	  && elf_section_type (section) != SHT_NOTE)
 	flags &= ~SEC_HAS_CONTENTS;
       else
 	flags &= ~SEC_ALLOC;
diff --git a/ld/testsuite/ld-elf/pr32787.d b/ld/testsuite/ld-elf/pr32787.d
new file mode 100644
index 00000000000..8d07b8d7914
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr32787.d
@@ -0,0 +1,9 @@
+#source: start.s
+#ld: --build-id -T pr32787.t
+#nm: -n
+# The following targets don't support --build-id.
+#xfail: [uses_genelf]
+
+#...
+.* start
+#pass
diff --git a/ld/testsuite/ld-elf/pr32787.t b/ld/testsuite/ld-elf/pr32787.t
new file mode 100644
index 00000000000..cf5aeb18ad1
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr32787.t
@@ -0,0 +1,12 @@
+SECTIONS {
+	. = SIZEOF_HEADERS;
+	.text : {
+		*(.text)
+	}
+	.data : {
+		_data_start = .;
+		*(.data)
+	}
+	.note.gnu.build-id (NOLOAD) : { *(.note.gnu.build-id) }
+	/DISCARD/ : { *(*) }
+}