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

[Tony Ambardar]

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.ambar...@gmail.com>
---
 include/linux/btf_ids.h | 1 +
 1 file changed, 1 insertion(+)

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");
-- 
2.34.1