On Tue, Mar 10, 2020 at 04:32:28PM +0900, Yoshiki Komachi wrote:
> btf_enum_check_member() checked if the size of "enum" as a struct
> member exceeded struct_size or not. Then, the function compared it
> with the size of "int". Although the size of "enum" is 4-byte by
> default (i.e., equivalent to "int"), the packing feature enables
> us to reduce it, as illustrated by the following example:
>
> struct A {
> char m;
> enum { E0, E1 } __attribute__((packed)) n;
> };
>
> With such a setup above, the bpf loader gave an error attempting
> to load it:
>
> ------------------------------------------------------------------
> ...
>
> [3] ENUM (anon) size=1 vlen=2
> E0 val=0
> E1 val=1
> [4] STRUCT A size=2 vlen=2
> m type_id=2 bits_offset=0
> n type_id=3 bits_offset=8
>
> [4] STRUCT A size=2 vlen=2
> n type_id=3 bits_offset=8 Member exceeds struct_size
>
> libbpf: Error loading .BTF into kernel: -22.
>
> ------------------------------------------------------------------
>
> The related issue was previously fixed by the commit 9eea98497951 ("bpf:
> fix BTF verification of enums"). On the other hand, this series fixes
> this issue as well, and adds a selftest program for it.
>
> Changes in v2:
> - change an example in commit message based on Andrii's review
> - add a selftest program for packed "enum" type members in struct/union
Acked-by: Martin KaFai Lau <kafai@xxxxxx>
