netdev - Re: [PATCH v2 bpf-next 02/11] libbpf: extract BTF loading logic

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Date:   Mon, 17 Jun 2019 19:40:00 +0000
From:   Song Liu <songliubraving@...com>
To:     Andrii Nakryiko <andriin@...com>
CC:     Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Alexei Starovoitov <ast@...com>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        Kernel Team <Kernel-team@...com>
Subject: Re: [PATCH v2 bpf-next 02/11] libbpf: extract BTF loading logic



> On Jun 17, 2019, at 12:26 PM, Andrii Nakryiko <andriin@...com> wrote:
> 
> As a preparetion fro adding BTF-based BPF map loading, extract .BTF and
> .BTF.ext loading logic.
> 
> Signed-off-by: Andrii Nakryiko <andriin@...com>

Acked-by: Song Liu <songliubraving@...com>

> ---
> tools/lib/bpf/libbpf.c | 93 +++++++++++++++++++++++++-----------------
> 1 file changed, 55 insertions(+), 38 deletions(-)
> 
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index e725fa86b189..49d3a808e754 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -1078,6 +1078,58 @@ static void bpf_object__sanitize_btf_ext(struct bpf_object *obj)
> 	}
> }
> 
> +static int bpf_object__load_btf(struct bpf_object *obj,
> +				Elf_Data *btf_data,
> +				Elf_Data *btf_ext_data)
> +{
> +	int err = 0;
> +
> +	if (btf_data) {
> +		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
> +		if (IS_ERR(obj->btf)) {
> +			pr_warning("Error loading ELF section %s: %d.\n",
> +				   BTF_ELF_SEC, err);
> +			goto out;
> +		}
> +		err = btf__finalize_data(obj, obj->btf);
> +		if (err) {
> +			pr_warning("Error finalizing %s: %d.\n",
> +				   BTF_ELF_SEC, err);
> +			goto out;
> +		}
> +		bpf_object__sanitize_btf(obj);
> +		err = btf__load(obj->btf);
> +		if (err) {
> +			pr_warning("Error loading %s into kernel: %d.\n",
> +				   BTF_ELF_SEC, err);
> +			goto out;
> +		}
> +	}
> +	if (btf_ext_data) {
> +		if (!obj->btf) {
> +			pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
> +				 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
> +			goto out;
> +		}
> +		obj->btf_ext = btf_ext__new(btf_ext_data->d_buf,
> +					    btf_ext_data->d_size);
> +		if (IS_ERR(obj->btf_ext)) {
> +			pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
> +				   BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext));
> +			obj->btf_ext = NULL;
> +			goto out;
> +		}
> +		bpf_object__sanitize_btf_ext(obj);
> +	}
> +out:
> +	if (err || IS_ERR(obj->btf)) {
> +		if (!IS_ERR_OR_NULL(obj->btf))
> +			btf__free(obj->btf);
> +		obj->btf = NULL;
> +	}
> +	return 0;
> +}
> +
> static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
> {
> 	Elf *elf = obj->efile.elf;
> @@ -1212,44 +1264,9 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
> 		pr_warning("Corrupted ELF file: index of strtab invalid\n");
> 		return -LIBBPF_ERRNO__FORMAT;
> 	}
> -	if (btf_data) {
> -		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
> -		if (IS_ERR(obj->btf)) {
> -			pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
> -				   BTF_ELF_SEC, PTR_ERR(obj->btf));
> -			obj->btf = NULL;
> -		} else {
> -			err = btf__finalize_data(obj, obj->btf);
> -			if (!err) {
> -				bpf_object__sanitize_btf(obj);
> -				err = btf__load(obj->btf);
> -			}
> -			if (err) {
> -				pr_warning("Error finalizing and loading %s into kernel: %d. Ignored and continue.\n",
> -					   BTF_ELF_SEC, err);
> -				btf__free(obj->btf);
> -				obj->btf = NULL;
> -				err = 0;
> -			}
> -		}
> -	}
> -	if (btf_ext_data) {
> -		if (!obj->btf) {
> -			pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
> -				 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
> -		} else {
> -			obj->btf_ext = btf_ext__new(btf_ext_data->d_buf,
> -						    btf_ext_data->d_size);
> -			if (IS_ERR(obj->btf_ext)) {
> -				pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
> -					   BTF_EXT_ELF_SEC,
> -					   PTR_ERR(obj->btf_ext));
> -				obj->btf_ext = NULL;
> -			} else {
> -				bpf_object__sanitize_btf_ext(obj);
> -			}
> -		}
> -	}
> +	err = bpf_object__load_btf(obj, btf_data, btf_ext_data);
> +	if (err)
> +		return err;
> 	if (bpf_object__has_maps(obj)) {
> 		err = bpf_object__init_maps(obj, flags);
> 		if (err)
> -- 
> 2.17.1
>