When redirecting the split BTF to the vmlinux base BTF, we need to mark
the distilled base struct/union members of split BTF structs/unions in
id_map with BTF_IS_EMBEDDED. This indicates that these types must match
both name and size later. So if a needed composite type, which is the
member of composite type in the split BTF, has a different size in the
base BTF we wish to relocate with, btf__relocate() should error out.
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250115100241.4171581-4-pulehui@huaweicloud.com
Test generation of split+distilled base BTF, ensuring that
- named base BTF STRUCTs and UNIONs are represented as 0-vlen sized
STRUCT/UNIONs
- named ENUM[64]s are represented as 0-vlen named ENUM[64]s
- anonymous struct/unions are represented in full in split BTF
- anonymous enums are represented in full in split BTF
- types unreferenced from split BTF are not present in distilled
base BTF
Also test that with vmlinux BTF and split BTF based upon it,
we only represent needed base types referenced from split BTF
in distilled base.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20240613095014.357981-3-alan.maguire@oracle.com
