From: Dave Marchevsky <davemarchevsky@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, Networking <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
John Fastabend <john.fastabend@gmail.com>
Subject: Re: [PATCH v2 bpf-next 1/2] bpf: add verified_insns to bpf_prog_info and fdinfo
Date: Wed, 20 Oct 2021 04:03:55 -0400 [thread overview]
Message-ID: <549f7100-ce3f-4754-a048-a2c824139a02@fb.com> (raw)
In-Reply-To: <CAEf4BzaMgv5otr9AQGHZW=sUCuBdt_Vkv_GqB9n8BYVcZWHjAQ@mail.gmail.com>
On 10/18/21 5:22 PM, Andrii Nakryiko wrote:
> On Mon, Oct 11, 2021 at 1:54 PM Dave Marchevsky <davemarchevsky@fb.com> wrote:
>>
>> This stat is currently printed in the verifier log and not stored
>> anywhere. To ease consumption of this data, add a field to bpf_prog_aux
>> so it can be exposed via BPF_OBJ_GET_INFO_BY_FD and fdinfo.
>>
>> Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
>> ---
>> include/linux/bpf.h | 1 +
>> include/uapi/linux/bpf.h | 2 +-
>> kernel/bpf/syscall.c | 8 ++++++--
>> kernel/bpf/verifier.c | 1 +
>> tools/include/uapi/linux/bpf.h | 2 +-
>> 5 files changed, 10 insertions(+), 4 deletions(-)
>>
>
> [...]
>
>> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
>> index 6fc59d61937a..d053fc7e7995 100644
>> --- a/tools/include/uapi/linux/bpf.h
>> +++ b/tools/include/uapi/linux/bpf.h
>> @@ -5591,7 +5591,7 @@ struct bpf_prog_info {
>> char name[BPF_OBJ_NAME_LEN];
>> __u32 ifindex;
>> __u32 gpl_compatible:1;
>> - __u32 :31; /* alignment pad */
>> + __u32 verified_insns:31;
>
> These 31 unused bits seem like a good place to add extra generic
> flags, not new counters. E.g., like a sleepable flag. So I wonder if
> it's better to use a dedicated u32 field for counters like
> verified_insns and keep these reserved fields for boolean flags?
>
> Daniel, I know you proposed to reuse those 31 bits. How strong do you
> feel about this? For any other kind of counter we seem to be using a
> complete dedicated integer field, so it would be consistent to keep
> doing that?
>
> Having a sleepable bit still seems like a good idea, btw :) but it's a
> separate change from Dave's.
Re: use padding vs new field, I don't have a strong feeling either way,
but if there are proper flags that could use that space in the near
future, this combined with consistency with other counters leans me
towards adding a new field.
Also, when using the bitfield space, clang complains about types in
selftest assert:
tools/testing/selftests/bpf/prog_tests/verif_stats.c:23:17: error: ‘typeof’ applied to a bit-field
23 | if (!ASSERT_GT(info.verified_insns, 0, "verified_insns"))
| ^~~~
./test_progs.h:227:9: note: in definition of macro ‘ASSERT_GT’
227 | typeof(actual) ___act = (actual); \
Which necessitated a __u32 cast in this version of the patchset. Don't think
it would cause issues outside of this specific selftest, but worth noting.
Anyways, sent a v3 of the patchset with 'new field' and other comments
addressed.
next prev parent reply other threads:[~2021-10-20 8:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-11 20:54 [PATCH v2 bpf-next 0/2] bpf: keep track of verifier insn_processed Dave Marchevsky
2021-10-11 20:54 ` [PATCH v2 bpf-next 1/2] bpf: add verified_insns to bpf_prog_info and fdinfo Dave Marchevsky
2021-10-18 21:22 ` Andrii Nakryiko
2021-10-20 8:03 ` Dave Marchevsky [this message]
2021-10-11 20:54 ` [PATCH v2 bpf-next 2/2] selftests/bpf: add verif_stats test Dave Marchevsky
2021-10-18 21:24 ` Andrii Nakryiko
2021-10-18 16:03 ` [PATCH v2 bpf-next 0/2] bpf: keep track of verifier insn_processed John Fastabend
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=549f7100-ce3f-4754-a048-a2c824139a02@fb.com \
--to=davemarchevsky@fb.com \
--cc=andrii.nakryiko@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=john.fastabend@gmail.com \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.