On Tue, May 12, 2020 at 8:54 AM Yonghong Song <yhs@xxxxxx> wrote:
>
> Commit b121b341e598 ("bpf: Add PTR_TO_BTF_ID_OR_NULL
> support") adds a field btf_id_or_null_non0_off to
> bpf_prog->aux structure to indicate that the
> first ctx argument is PTR_TO_BTF_ID reg_type and
> all others are PTR_TO_BTF_ID_OR_NULL.
> This approach does not really scale if we have
> other different reg types in the future, e.g.,
> a pointer to a buffer.
>
> This patch enables bpf_iter targets registering ctx argument
> reg types which may be different from the default one.
> For example, for pointers to structures, the default reg_type
> is PTR_TO_BTF_ID for tracing program. The target can register
> a particular pointer type as PTR_TO_BTF_ID_OR_NULL which can
> be used by the verifier to enforce accesses.
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
LGTM. It's cleaner approach than btf_id_or_null_non0_off, of course.
Having field annotations would be even better, but BTF doesn't have
attributes (yet).
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
> include/linux/bpf.h | 12 +++++++++++-
> include/net/ip6_fib.h | 7 +++++++
> kernel/bpf/bpf_iter.c | 5 +++++
> kernel/bpf/btf.c | 15 ++++++++++-----
> kernel/bpf/map_iter.c | 5 +++++
> kernel/bpf/task_iter.c | 12 ++++++++++++
> kernel/bpf/verifier.c | 1 -
> net/ipv6/ip6_fib.c | 5 -----
> net/ipv6/route.c | 5 +++++
> net/netlink/af_netlink.c | 5 +++++
> 10 files changed, 60 insertions(+), 12 deletions(-)
>
[...]
