Tony Ambardar 61e8aeda93 bpf: Fix libelf endian handling in resolv_btfids ... The vmlinux ".BTF_ids" ELF section is declared in btf_ids.h to hold a list of zero-filled BTF IDs, which is then patched at link-time with correct values by resolv_btfids. The section is flagged as "allocable" to preclude compression, but notably the section contents (BTF IDs) are untyped. When patching the BTF IDs, resolve_btfids writes in host-native endianness and relies on libelf for any required translation on reading and updating vmlinux. However, since the type of the .BTF_ids section content defaults to ELF_T_BYTE (i.e. unsigned char), no translation occurs. This results in incorrect patched values when cross-compiling to non-native endianness, and can manifest as kernel Oops and test failures which are difficult to troubleshoot [1]. Explicitly set the type of patched data to ELF_T_WORD, the architecture- neutral ELF type corresponding to the u32 BTF IDs. This enables libelf to transparently perform any needed endian conversions. Fixes: fbbb68de80 ("bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object") Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Jiri Olsa <jolsa@redhat.com> Cc: Frank Eigler <fche@redhat.com> Cc: Mark Wielaard <mark@klomp.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/CAPGftE_eY-Zdi3wBcgDfkz_iOr1KF10n=9mJHm1_a_PykcsoeA@mail.gmail.com [1] Link: https://lore.kernel.org/bpf/20210618061404.818569-1-Tony.Ambardar@gmail.com		2021-06-18 17:01:00 +02:00
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.gitignore	tools/resolve_btfids: Add /libbpf to .gitignore	2021-02-12 13:08:26 -08:00
Build	bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object	2020-07-13 10:42:02 -07:00
main.c	bpf: Fix libelf endian handling in resolv_btfids	2021-06-18 17:01:00 +02:00
Makefile	tools/resolve_btfids: Set srctree variable unconditionally	2021-02-08 21:21:39 -08:00