From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "Eduard Zingerman" <eddyz87@gmail.com>, <bpf@vger.kernel.org>,
<ast@kernel.org>
Cc: <andrii@kernel.org>, <daniel@iogearbox.net>,
<martin.lau@linux.dev>, <kernel-team@fb.com>,
<yonghong.song@linux.dev>, <shung-hsi.yu@suse.com>,
<paul.chaignon@gmail.com>, <harishankar.vishwanathan@gmail.com>
Subject: Re: [PATCH bpf-next v2 0/4] bpf: replace min/max fields with struct cnum{32,64}
Date: Fri, 24 Apr 2026 07:27:41 -0700 [thread overview]
Message-ID: <DI1GETNIDN91.BJPVEP02OODT@gmail.com> (raw)
In-Reply-To: <20260424-cnums-everywhere-rfc-v1-v2-0-57091924c9d7@gmail.com>
On Fri Apr 24, 2026 at 1:17 AM PDT, Eduard Zingerman wrote:
> This RFC replaces s64, u64, s32, u32 scalar range domains tracked by
> verifier by a pair of circular numbers (cnums): one for 64-bit domain
> and another for 32-bit domain. Each cnum represents a range as a
> single arc on the circular number line, from which signed and unsigned
> bounds are derived on demand. See also wrapped intervals
> representation as in [1].
>
> The use of such representation simplifies arithmetic and conditions
> handling in verifier.c and allows to express 32 <-> 64 bit deductions
> in a more mathematically rigorous way.
>
> [1] https://jorgenavas.github.io/papers/ACM-TOPLAS-wrapped.pdf
>
> Changelog
> =========
> RFCv1 -> v2:
> - Dropped RFC tag.
> - Dropped cnum{32,64}_mul(), too much complexity and no veristat
> or selftests gains.
Nice. Less complexity the better.
I think it's also strong signal that _div(), _mod() versions are not
needed either.
next prev parent reply other threads:[~2026-04-24 14:27 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-24 8:17 [PATCH bpf-next v2 0/4] bpf: replace min/max fields with struct cnum{32,64} Eduard Zingerman
2026-04-24 8:17 ` [PATCH bpf-next v2 1/4] bpf: representation and basic operations on circular numbers Eduard Zingerman
2026-04-24 9:00 ` bot+bpf-ci
2026-04-24 17:26 ` Eduard Zingerman
2026-04-24 8:17 ` [PATCH bpf-next v2 2/4] bpf: use accessor functions for bpf_reg_state min/max fields Eduard Zingerman
2026-04-24 8:17 ` [PATCH bpf-next v2 3/4] bpf: replace min/max fields with struct cnum{32,64} Eduard Zingerman
2026-04-24 9:12 ` bot+bpf-ci
2026-04-24 17:21 ` Eduard Zingerman
2026-04-24 8:17 ` [PATCH bpf-next v2 4/4] selftests/bpf: new cases handled by 32->64 range refinements Eduard Zingerman
2026-04-24 14:27 ` Alexei Starovoitov [this message]
2026-04-24 19:01 ` [PATCH bpf-next v2 0/4] bpf: replace min/max fields with struct cnum{32,64} Eduard Zingerman
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