From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>, bpf <bpf@vger.kernel.org>,
Networking <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v6 bpf-next 10/14] bpf: allow to specify kernel module BTFs when attaching BPF programs
Date: Fri, 4 Dec 2020 11:31:37 -0800 [thread overview]
Message-ID: <CAEf4BzbqneM9bXn646EpNAnaZr=sStqf6guBvWvf9qtyDYO9mg@mail.gmail.com> (raw)
In-Reply-To: <20201204015358.sk5zl5l73zmcu7t2@ast-mbp>
On Thu, Dec 3, 2020 at 5:54 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Thu, Dec 03, 2020 at 12:46:30PM -0800, Andrii Nakryiko wrote:
> > + if (attr->attach_prog_fd) {
> > + dst_prog = bpf_prog_get(attr->attach_prog_fd);
> > + if (IS_ERR(dst_prog)) {
> > + dst_prog = NULL;
> > + attach_btf = btf_get_by_fd(attr->attach_btf_obj_fd);
> > + if (IS_ERR(attach_btf))
> > + return -EINVAL;
> > + if (!btf_is_kernel(attach_btf)) {
> > + btf_put(attach_btf);
> > + return -EINVAL;
>
> Applied, but please consider follow up with different err code here.
> I think we might support this case in the future.
> Specifying prog's BTF as a base and attach_btf_id within it might make
> user space simpler in some cases. prog's btf covers the whole elf file.
The problem is that there is no link from BTF to bpf_prog. And
multiple instances of bpf_progs can re-use the same BTF object and the
same BTF type ID. That would need to be resolved somehow.
But keeping our options open is a good idea either way. So I'll send a
patch to switch this to -EOPNOTSUPP (I think that's the one we need to
use for user-space).
> Where prog_fd is a specific prog. That narrow scope isn't really necessary.
> So may be return ENOTSUPP here for now? With a hint that this might
> work in the future?
next prev parent reply other threads:[~2020-12-04 19:32 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 20:46 [PATCH v6 bpf-next 00/14] Support BTF-powered BPF tracing programs for kernel modules Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 01/14] bpf: fix bpf_put_raw_tracepoint()'s use of __module_address() Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 02/14] bpf: keep module's btf_data_size intact after load Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 03/14] libbpf: add internal helper to load BTF data by FD Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 04/14] libbpf: refactor CO-RE relocs to not assume a single BTF object Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 05/14] libbpf: add kernel module BTF support for CO-RE relocations Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 06/14] selftests/bpf: add bpf_testmod kernel module for testing Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 07/14] selftests/bpf: add support for marking sub-tests as skipped Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 08/14] selftests/bpf: add CO-RE relocs selftest relying on kernel module BTF Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 09/14] bpf: remove hard-coded btf_vmlinux assumption from BPF verifier Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 10/14] bpf: allow to specify kernel module BTFs when attaching BPF programs Andrii Nakryiko
2020-12-04 1:53 ` Alexei Starovoitov
2020-12-04 19:31 ` Andrii Nakryiko [this message]
2020-12-03 20:46 ` [PATCH v6 bpf-next 11/14] libbpf: factor out low-level BPF program loading helper Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 12/14] libbpf: support attachment of BPF tracing programs to kernel modules Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 13/14] selftests/bpf: add tp_btf CO-RE reloc test for modules Andrii Nakryiko
2020-12-03 20:46 ` [PATCH v6 bpf-next 14/14] selftests/bpf: add fentry/fexit/fmod_ret selftest for kernel module Andrii Nakryiko
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