From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, "Alexei Starovoitov" <ast@kernel.org>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Toke Høiland-Jørgensen" <toke@redhat.com>,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
netfilter-devel <netfilter-devel@vger.kernel.org>,
"Network Development" <netdev@vger.kernel.org>
Subject: Re: [PATCH bpf-next v1 03/15] bpf: Allow storing PTR_TO_BTF_ID in map
Date: Wed, 23 Feb 2022 13:46:54 -0800 [thread overview]
Message-ID: <CAADnVQLdLmD1BUfDozvFs4YiTD=4aN43iJdn4TZ9hB7SBM-bAw@mail.gmail.com> (raw)
In-Reply-To: <20220223030925.uxevhkloz7dznkal@apollo.legion>
On Tue, Feb 22, 2022 at 7:09 PM Kumar Kartikeya Dwivedi
<memxor@gmail.com> wrote:
> > > + }
> > > + btf_id_tag = true;
> > > + } else if (!strncmp("kernel.", __btf_name_by_offset(btf, t->name_off),
> > > + sizeof("kernel.") - 1)) {
> > > + /* TODO: Should we reject these when loading BTF? */
> > > + /* Unavailable tag in reserved tag namespace */
> >
> > I don't think we need to reserve the tag space.
> > There is little risk to break progs with future tags.
> > I would just drop this 'if'.
> >
>
> Fine with dropping, but what is the expected behavior when userspace has set a
> tag in map value BTF that we give some meaning in the kernel later?
All of these features fall into the unstable category.
kfuncs can disappear. kernel data structs can get renamed.
dtor, kptr_get functions not only can change, but can be removed.
When bpf progs are so tightly interacting with the kernel they
have to change and adjust.
Eventually we might bolt a bit of CO-RE like logic to kfunc and kptr
to make things more portable, but it's too early to reserve a btf_tag prefix.
Progs will change. We're not saving users any headache with reservation.
Tracing bpf progs are not user space. That's the key.
next prev parent reply other threads:[~2022-02-23 21:47 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-20 13:47 [PATCH bpf-next v1 00/15] Introduce typed pointer support in BPF maps Kumar Kartikeya Dwivedi
2022-02-20 13:47 ` [PATCH bpf-next v1 01/15] bpf: Factor out fd returning from bpf_btf_find_by_name_kind Kumar Kartikeya Dwivedi
2022-02-22 5:28 ` Alexei Starovoitov
2022-02-23 3:05 ` Kumar Kartikeya Dwivedi
2022-02-20 13:48 ` [PATCH bpf-next v1 02/15] bpf: Make btf_find_field more generic Kumar Kartikeya Dwivedi
2022-02-20 13:48 ` [PATCH bpf-next v1 03/15] bpf: Allow storing PTR_TO_BTF_ID in map Kumar Kartikeya Dwivedi
2022-02-22 6:46 ` Alexei Starovoitov
2022-02-23 3:09 ` Kumar Kartikeya Dwivedi
2022-02-23 21:46 ` Alexei Starovoitov [this message]
2022-02-20 13:48 ` [PATCH bpf-next v1 04/15] bpf: Allow storing referenced " Kumar Kartikeya Dwivedi
2022-02-22 6:53 ` Alexei Starovoitov
2022-02-22 7:10 ` Kumar Kartikeya Dwivedi
2022-02-22 16:20 ` Alexei Starovoitov
2022-02-23 3:04 ` Kumar Kartikeya Dwivedi
2022-02-23 21:52 ` Alexei Starovoitov
2022-02-24 8:43 ` Kumar Kartikeya Dwivedi
2022-02-20 13:48 ` [PATCH bpf-next v1 05/15] bpf: Allow storing PTR_TO_PERCPU_BTF_ID " Kumar Kartikeya Dwivedi
2022-02-20 20:40 ` kernel test robot
2022-02-20 13:48 ` [PATCH bpf-next v1 06/15] bpf: Allow storing __user PTR_TO_BTF_ID " Kumar Kartikeya Dwivedi
2022-02-20 13:48 ` [PATCH bpf-next v1 07/15] bpf: Prevent escaping of pointers loaded from maps Kumar Kartikeya Dwivedi
2022-02-20 13:48 ` [PATCH bpf-next v1 08/15] bpf: Adapt copy_map_value for multiple offset case Kumar Kartikeya Dwivedi
2022-02-22 7:04 ` Alexei Starovoitov
2022-02-23 3:13 ` Kumar Kartikeya Dwivedi
2022-02-23 21:41 ` Alexei Starovoitov
2022-02-20 13:48 ` [PATCH bpf-next v1 09/15] bpf: Populate pairs of btf_id and destructor kfunc in btf Kumar Kartikeya Dwivedi
2022-02-20 13:48 ` [PATCH bpf-next v1 10/15] bpf: Wire up freeing of referenced PTR_TO_BTF_ID in map Kumar Kartikeya Dwivedi
2022-02-20 21:43 ` kernel test robot
2022-02-20 22:55 ` kernel test robot
2022-02-21 0:39 ` kernel test robot
2022-02-20 13:48 ` [PATCH bpf-next v1 11/15] bpf: Teach verifier about kptr_get style kfunc helpers Kumar Kartikeya Dwivedi
2022-02-20 13:48 ` [PATCH bpf-next v1 12/15] net/netfilter: Add bpf_ct_kptr_get helper Kumar Kartikeya Dwivedi
2022-02-21 4:35 ` kernel test robot
2022-02-20 13:48 ` [PATCH bpf-next v1 13/15] libbpf: Add __kptr* macros to bpf_helpers.h Kumar Kartikeya Dwivedi
2022-02-20 13:48 ` [PATCH bpf-next v1 14/15] selftests/bpf: Add C tests for PTR_TO_BTF_ID in map Kumar Kartikeya Dwivedi
2022-02-20 13:48 ` [PATCH bpf-next v1 15/15] selftests/bpf: Add verifier " Kumar Kartikeya Dwivedi
2022-02-22 6:05 ` [PATCH bpf-next v1 00/15] Introduce typed pointer support in BPF maps Song Liu
2022-02-22 8:21 ` Kumar Kartikeya Dwivedi
2022-02-23 7:29 ` Song Liu
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