Re: [PATCH bpf-next v6 06/10] bpf: Add verifier support for 16-byte returns in R0:R2

> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index 5b9d767895c9..2ae7cb9b30f2 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -7684,6 +7684,12 @@ static int btf_check_func_type_match(struct bpf_verifier_log *log,
>  			btf_type_str(t2), fn2);
>  		return -EINVAL;
>  	}
> +	if (btf_type_has_size(t1) && (t1->size > 8 || t2->size > 8)) {
> +		bpf_log(log,
> +			"Return type of %s() has size %u while %s() has size %u, and a size above 8 bytes cannot be replaced\n",
> +			fn1, t1->size, fn2, t2->size);
> +		return -EINVAL;
> +	}

This isn't a bug, but since this check fires on the absolute size rather
than on a mismatch, the message can end up reading "has size 16 while g()
has size 16". Would it be clearer to state which side exceeds 8 bytes
instead of using the "X while Y" mismatch phrasing the neighbouring
diagnostics use?


---
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CI run summary: https://github.com/kernel-patches/bpf/actions/runs/31995069373