From: Eduard Zingerman <eddyz87@gmail.com>
To: Yonghong Song <yonghong.song@linux.dev>,
Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
kernel-team@fb.com, Martin KaFai Lau <martin.lau@kernel.org>,
Kuniyuki Iwashima <kuniyu@amazon.com>,
Martin KaFai Lau <kafai@fb.com>
Subject: Re: [PATCH bpf-next v2 1/2] bpf: Track aligned st store as imprecise spilled registers
Date: Mon, 08 Jan 2024 21:06:10 +0200 [thread overview]
Message-ID: <ec2758667b5a286dd48ebaaa8cfafa1112699735.camel@gmail.com> (raw)
In-Reply-To: <07d7d6e0-d090-47e6-9f17-0b083aeaa7af@linux.dev>
On Mon, 2024-01-08 at 10:59 -0800, Yonghong Song wrote:
[...]
> I guess one way could be doing backtracking with "... = arr[i]"
> is to have four ranges, [-32, -24), [-24, -16), [-16, -8), [-8, 0).
> Later, when we see arr[i] = r0 and i has range [-32, 0). Since it covers [-32, -24), etc.,
> precision marking can proceed with 'r0'. But I guess this can potentially
> increase verifier backtracking states a lot and is not scalable. Conservatively
> doing precision marking with 'r0' (in arr[i] = r0) is a better idea.
In theory it should be possible to collapse this range to min/max pair.
But it is a complication, and I'd say it shouldn't be implemented
unless we have evidence that it significantly improves verification
performance.
>
> Andrii has similar comments in
> https://lore.kernel.org/bpf/CAEf4Bzb0LdSPnFZ-kPRftofA6LsaOkxXLN4_fr9BLR3iG-te-g@mail.gmail.com/
>
next prev parent reply other threads:[~2024-01-08 19:06 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-03 23:26 [PATCH bpf-next v2 1/2] bpf: Track aligned st store as imprecise spilled registers Yonghong Song
2024-01-03 23:26 ` [PATCH bpf-next v2 2/2] selftests/bpf: Add a selftest with not-8-byte aligned BPF_ST Yonghong Song
2024-01-04 16:37 ` [PATCH bpf-next v2 1/2] bpf: Track aligned st store as imprecise spilled registers Eduard Zingerman
2024-01-04 17:13 ` Yonghong Song
2024-01-04 18:43 ` Eduard Zingerman
2024-01-04 18:30 ` Eduard Zingerman
2024-01-04 20:12 ` Yonghong Song
2024-01-04 21:10 ` Eduard Zingerman
2024-01-04 23:09 ` Andrii Nakryiko
2024-01-04 23:29 ` Eduard Zingerman
2024-01-05 1:05 ` Andrii Nakryiko
2024-01-05 7:14 ` Yonghong Song
2024-01-05 8:10 ` Yonghong Song
2024-01-05 23:37 ` Eduard Zingerman
2024-01-08 18:59 ` Yonghong Song
2024-01-08 19:06 ` Eduard Zingerman [this message]
2024-01-08 19:40 ` Yonghong Song
2024-01-05 23:52 ` Eduard Zingerman
2024-01-08 19:51 ` Yonghong Song
2024-01-08 20:05 ` Eduard Zingerman
2024-01-08 21:51 ` Yonghong Song
2024-01-08 23:18 ` Andrii Nakryiko
2024-01-04 23:03 ` Andrii Nakryiko
2024-01-05 0:49 ` Andrii Nakryiko
2024-01-08 23:23 ` Andrii Nakryiko
2024-01-08 23:39 ` Yonghong Song
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=ec2758667b5a286dd48ebaaa8cfafa1112699735.camel@gmail.com \
--to=eddyz87@gmail.com \
--cc=andrii.nakryiko@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kafai@fb.com \
--cc=kernel-team@fb.com \
--cc=kuniyu@amazon.com \
--cc=martin.lau@kernel.org \
--cc=yonghong.song@linux.dev \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox