[PATCH v3 1/2] objcopy: Fix --only-keep-debug for ELF relocatables
Peilin Ye
yepeilin.cs@gmail.com
Tue Feb 1 00:20:46 GMT 2022
From: Peilin Ye <peilin.ye@bytedance.com>
objcopy's --only-keep-debug option has been broken for ELF relocatables
since commit 8c803a2dd7d3 ("elf_backend_section_flags and
_bfd_elf_init_private_section_data"):
1. binutils/objcopy.c:setup_section() marks non-debug OSECs as
SHT_NOBITS, then calls bfd_copy_private_section_data(), see
"mark_nobits";
2. If ISEC and OSEC share the same section flags,
bfd/elf.c:_bfd_elf_init_private_section_data() restores OSEC's
section type back to ISEC's section type, effectively undoing
"mark_nobits".
This makes objcopy's --only-keep-debug a no-op for ELF relocatables. As
an example, Linux's scripts/package/builddeb script depends on this
option to generate debug-info-only kernel (.ko) modules.
As suggested by Nick and Alan, fix --only-keep-debug by marking
non-debug OSECs as SHT_NOBITS after calling
bfd_copy_private_section_data() in setup_section().
binutils/ChangeLog:
* objcopy.c (setup_section): For --only-keep-debug, mark
non-debug output sections as SHT_NOBITS after calling
bfd_copy_private_section_data()
Reported-by: Omar Sandoval <osandov@osandov.com>
Fixes: 8c803a2dd7d3 ("elf_backend_section_flags and _bfd_elf_init_private_section_data")
Suggested-by: Alan Modra <amodra@gmail.com>
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
---
change since v2:
- mention ELF relocatables in commit message
change since v1:
- fix objcopy instead of touching _bfd_elf_init_private_section_data()
(suggested by Nick and Alan)
binutils/objcopy.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/binutils/objcopy.c b/binutils/objcopy.c
index d16d8ee67e4d..d53aa5c6000f 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -4085,9 +4085,6 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
goto loser;
}
- if (make_nobits)
- elf_section_type (osection) = SHT_NOBITS;
-
size = bfd_section_size (isection);
size = bfd_convert_section_size (ibfd, isection, obfd, size);
if (copy_byte >= 0)
@@ -4181,6 +4178,9 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
goto loser;
}
+ if (make_nobits)
+ elf_section_type (osection) = SHT_NOBITS;
+
/* All went well. */
return;
--
2.20.1
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