Re: [PATCH bpf-next 2/5] libbpf: make use of BTF field iterator in BPF linker code

[Jiri Olsa <olsajiri@gmail.com>]

On Mon, Jun 03, 2024 at 04:17:16PM -0700, Andrii Nakryiko wrote:
> Switch all BPF linker code dealing with iterating BTF type ID and string
> offset fields to new btf_field_iter facilities.
> 
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
> ---
>  tools/lib/bpf/linker.c | 60 ++++++++++++++++++++++++++----------------
>  1 file changed, 38 insertions(+), 22 deletions(-)
> 
> diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
> index 0d4be829551b..be6539e59cf6 100644
> --- a/tools/lib/bpf/linker.c
> +++ b/tools/lib/bpf/linker.c
> @@ -957,19 +957,35 @@ static int check_btf_str_off(__u32 *str_off, void *ctx)
>  static int linker_sanity_check_btf(struct src_obj *obj)
>  {
>  	struct btf_type *t;
> -	int i, n, err = 0;
> +	int i, n, err;
>  
>  	if (!obj->btf)
>  		return 0;
>  
>  	n = btf__type_cnt(obj->btf);
>  	for (i = 1; i < n; i++) {
> +		struct btf_field_iter it;
> +		__u32 *type_id, *str_off;
> +		const char *s;
> +
>  		t = btf_type_by_id(obj->btf, i);
>  
> -		err = err ?: btf_type_visit_type_ids(t, check_btf_type_id, obj->btf);
> -		err = err ?: btf_type_visit_str_offs(t, check_btf_str_off, obj->btf);
> +		err = btf_field_iter_init(&it, t, BTF_FIELD_ITER_IDS);
>  		if (err)
>  			return err;
> +		while ((type_id = btf_field_iter_next(&it))) {
> +			if (*type_id >= n)
> +				return -EINVAL;
> +		}
> +
> +		err = btf_field_iter_init(&it, t, BTF_FIELD_ITER_STRS);
> +		if (err)
> +			return err;
> +		while ((str_off = btf_field_iter_next(&it))) {
> +			s = btf__str_by_offset(obj->btf, *str_off);
> +			if (!s)
> +				return -EINVAL;

nit, we could drop 's' and just do (!btf__str_by_offset(obj->btf, *str_off))


otherwise the patchset lgtm

Acked-by: Jiri Olsa <jolsa@kernel.org>

jirka

> +		}
>  	}
>  
>  	return 0;
> @@ -2234,26 +2250,10 @@ static int linker_fixup_btf(struct src_obj *obj)
>  	return 0;
>  }

SNIP