[PATCH] D83289: [BPF] Emit unknown types as byte arrays

[Alexei Starovoitov via Phabricator via llvm-commits]

ast added a comment.

'float *var;' in the struct won't be trivial to handle with a skip indeed.
My concern with float->char[] substitute is that the kernel decides on calling convention based on these types.
If there is a function fn(int a, float b); and pahole emits BTF for it as fn(int a, char b[4])
the kernel will let bpf progs to attach to it with wrong register passing.
Currently array is not allowed in btf_distill_func_proto(), so it's a theoretical issue, but still dangerous long term.
I think pahole/clang should either skip generating BTF for anything with float or BTF should be extended to encode it.
I think extending BTF would be easier.
I don't like KIND_INT_FLOATING though. KIND_FLOAT is better. Just like single KIND_INT that represents char/int/long
the KIND_FLOAT should be able to represent float/double/long double.


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https://reviews.llvm.org/D83289