On Fri, Mar 19, 2021 at 9:16 PM Rafael David Tinoco
<rafaeldtinoco@xxxxxxxxxx> wrote:
>
> Unfortunately some distros don't have their kernel version defined
> accurately in <linux/version.h> due to different long term support
> reasons.
>
> It is important to have a way to override the bpf kern_version
> attribute during runtime: some old kernels might still check for
> kern_version attribute during bpf_prog_load().
>
> Signed-off-by: Rafael David Tinoco <rafaeldtinoco@xxxxxxxxxx>
> ---
> src/libbpf.c | 15 +++++++++++++++
> src/libbpf.h | 1 +
> 2 files changed, 16 insertions(+)
>
> diff --git a/src/libbpf.c b/src/libbpf.c
> index 0c4a386..7b52cd6 100644
> --- a/src/libbpf.c
> +++ b/src/libbpf.c
> @@ -8278,6 +8278,21 @@ int bpf_object__btf_fd(const struct bpf_object *obj)
> return obj->btf ? btf__fd(obj->btf) : -1;
> }
>
> +int bpf_object__set_kversion(struct bpf_object *obj, char *kern_version)
> +{
> + __u32 major, minor, patch;
> +
> + if (!kern_version) {
> + obj->kern_version = 0;
> + return 0;
> + }
> + if (sscanf(kern_version, "%u.%u.%u", &major, &minor, &patch) != 3)
given SEC("version") expects `int` and bpf_object__kversion() returns
int, I think it's appropriate for bpf_object__set_kversion() to accept
just opaque int as well. Please also check that obj is not loaded and
return error if it is. Thanks!
> + return -1;
> + obj->kern_version = KERNEL_VERSION(major, minor, patch);
> +
> + return 0;
> +}
> +
> int bpf_object__set_priv(struct bpf_object *obj, void *priv,
> bpf_object_clear_priv_t clear_priv)
> {
> diff --git a/src/libbpf.h b/src/libbpf.h
> index 3c35eb4..3e14ae7 100644
> --- a/src/libbpf.h
> +++ b/src/libbpf.h
> @@ -143,6 +143,7 @@ LIBBPF_API int bpf_object__unload(struct bpf_object *obj);
>
> LIBBPF_API const char *bpf_object__name(const struct bpf_object *obj);
> LIBBPF_API unsigned int bpf_object__kversion(const struct bpf_object *obj);
> +LIBBPF_API int bpf_object__set_kversion(struct bpf_object *obj, char *kern_version);
>
> struct btf;
> LIBBPF_API struct btf *bpf_object__btf(const struct bpf_object *obj);
> --
> 2.27.0
>
