From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>, bpf <bpf@vger.kernel.org>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v5 bpf-next 08/17] bpf: Add bpf_core_add_cands() and wire it into bpf_core_apply_relo_insn().
Date: Wed, 1 Dec 2021 17:25:05 -0800 [thread overview]
Message-ID: <CAEf4Bza+HxbG5FTPOCCKWqF-OfuoF94YMZP9Rqyz+dML-NuzbQ@mail.gmail.com> (raw)
In-Reply-To: <20211201181040.23337-9-alexei.starovoitov@gmail.com>
On Wed, Dec 1, 2021 at 10:11 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> From: Alexei Starovoitov <ast@kernel.org>
>
> Given BPF program's BTF root type name perform the following steps:
> . search in vmlinux candidate cache.
> . if (present in cache and candidate list >= 1) return candidate list.
> . do a linear search through kernel BTFs for possible candidates.
> . regardless of number of candidates found populate vmlinux cache.
> . if (candidate list >= 1) return candidate list.
> . search in module candidate cache.
> . if (present in cache) return candidate list (even if list is empty).
> . do a linear search through BTFs of all kernel modules
> collecting candidates from all of them.
> . regardless of number of candidates found populate module cache.
> . return candidate list.
> Then wire the result into bpf_core_apply_relo_insn().
>
> When BPF program is trying to CO-RE relocate a type
> that doesn't exist in either vmlinux BTF or in modules BTFs
> these steps will perform 2 cache lookups when cache is hit.
>
> Note the cache doesn't prevent the abuse by the program that might
> have lots of relocations that cannot be resolved. Hence cond_resched().
>
> CO-RE in the kernel requires CAP_BPF, since BTF loading requires it.
>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> ---
Looks correct as far as I can tell.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
> kernel/bpf/btf.c | 346 ++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 345 insertions(+), 1 deletion(-)
>
[...]
next prev parent reply other threads:[~2021-12-02 1:25 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-01 18:10 [PATCH v5 bpf-next 00/17] bpf: CO-RE support in the kernel Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 01/17] libbpf: Replace btf__type_by_id() with btf_type_by_id() Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 02/17] bpf: Rename btf_member accessors Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 03/17] bpf: Prepare relo_core.c for kernel duty Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 04/17] bpf: Define enum bpf_core_relo_kind as uapi Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 05/17] bpf: Pass a set of bpf_core_relo-s to prog_load command Alexei Starovoitov
2022-04-20 11:32 ` Jakub Sitnicki
2022-04-20 16:50 ` Andrii Nakryiko
2022-04-25 16:09 ` Jakub Sitnicki
2021-12-01 18:10 ` [PATCH v5 bpf-next 06/17] bpf: Adjust BTF log size limit Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 07/17] libbpf: Cleanup struct bpf_core_cand Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 08/17] bpf: Add bpf_core_add_cands() and wire it into bpf_core_apply_relo_insn() Alexei Starovoitov
2021-12-02 1:25 ` Andrii Nakryiko [this message]
2021-12-01 18:10 ` [PATCH v5 bpf-next 09/17] libbpf: Use CO-RE in the kernel in light skeleton Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 10/17] libbpf: Support init of inner maps " Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 11/17] libbpf: Clean gen_loader's attach kind Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 12/17] selftests/bpf: Add lskel version of kfunc test Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 13/17] selftests/bpf: Improve inner_map test coverage Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 14/17] selftests/bpf: Convert map_ptr_kern test to use light skeleton Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 15/17] selftests/bpf: Additional test for CO-RE in the kernel Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 16/17] selftests/bpf: Revert CO-RE removal in test_ksyms_weak Alexei Starovoitov
2021-12-01 18:10 ` [PATCH v5 bpf-next 17/17] selftests/bpf: Add CO-RE relocations to verifier scale test Alexei Starovoitov
2021-12-02 18:44 ` [PATCH v5 bpf-next 00/17] bpf: CO-RE support in the kernel Matteo Croce
2021-12-03 19:18 ` Alexei Starovoitov
2021-12-03 19:23 ` Matteo Croce
2021-12-02 19:42 ` Andrii Nakryiko
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