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[bpf-next,v1,2/3] bpf: btf: Ensure natural alignment of .BTF_ids section

Message ID 714d7ab8a48172c67ddc027c85b2a0dad0312a74.1726806756.git.tony.ambardar@gmail.com (mailing list archive)
State New
Headers show
Series Improve .BTF_ids patching and alignment | expand

Commit Message

Tony Ambardar Sept. 20, 2024, 7:49 a.m. UTC 
While building of vmlinux employs a linker script to align the .BTF_ids
section to 4 bytes, other usage leaves .BTF_ids unaligned and may lead to
problems (e.g. [1]). Post-processing and libelf-based endian translation by
resolve_btfids may also potentially suffer from misalignment.

Update encoding macros in btf_ids.h to always align BTF ID data to 4 bytes.

[1]: 3effc06a4dde ("selftests/bpf: Fix alignment of .BTF_ids")

Signed-off-by: Tony Ambardar <tony.ambardar@gmail.com>
---
 include/linux/btf_ids.h | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
index c0e3e1426a82..c10b163dc340 100644
--- a/include/linux/btf_ids.h
+++ b/include/linux/btf_ids.h
@@ -89,6 +89,7 @@  word							\
 #define __BTF_ID_LIST(name, scope)			\
 asm(							\
 ".pushsection " BTF_IDS_SECTION ",\"a\";       \n"	\
+".balign 4, 0;                                 \n"	\
 "." #scope " " #name ";                        \n"	\
 #name ":;                                      \n"	\
 ".popsection;                                  \n");