From: Eduard Zingerman <eddyz87@gmail.com>
To: Andrii Nakryiko <andrii@kernel.org>,
bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
martin.lau@kernel.org
Cc: kernel-team@meta.com
Subject: Re: [PATCH bpf-next 05/13] bpf: remove redundant s{32,64} -> u{32,64} deduction logic
Date: Sat, 04 Nov 2023 00:16:59 +0200 [thread overview]
Message-ID: <c06fb5b86ee4ea724d674e23d99b084e9d9385a3.camel@gmail.com> (raw)
In-Reply-To: <20231103000822.2509815-6-andrii@kernel.org>
On Thu, 2023-11-02 at 17:08 -0700, Andrii Nakryiko wrote:
> Equivalent checks were recently added in more succinct and, arguably,
> safer form in:
> - f188765f23a5 ("bpf: derive smin32/smax32 from umin32/umax32 bounds");
> - 2e74aef782d3 ("bpf: derive smin/smax from umin/max bounds").
>
> The checks we are removing in this patch set do similar checks to detect
> if entire u32/u64 range has signed bit set or not set, but does it with
> two separate checks.
>
> Further, we forcefully overwrite either smin or smax (and 32-bit equvalents)
> without applying normal min/max intersection logic. It's not clear why
> that would be correct in all cases and seems to work by accident. This
> logic is also "gated" by previous signed -> unsigned derivation, which
> returns early.
>
> All this is quite confusing and seems error-prone, while we already have
> at least equivalent checks happening earlier. So remove this duplicate
> and error-prone logic to simplify things a bit.
>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
next prev parent reply other threads:[~2023-11-03 22:17 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-03 0:08 [PATCH bpf-next 00/13] BPF register bounds range vs range support Andrii Nakryiko
2023-11-03 0:08 ` [PATCH bpf-next 01/13] bpf: generalize reg_set_min_max() to handle non-const register comparisons Andrii Nakryiko
2023-11-03 7:52 ` Shung-Hsi Yu
2023-11-03 8:33 ` Shung-Hsi Yu
2023-11-03 20:39 ` Andrii Nakryiko
2023-11-03 20:48 ` Andrii Nakryiko
2023-11-06 2:22 ` Shung-Hsi Yu
2023-11-03 16:20 ` Eduard Zingerman
2023-11-03 20:39 ` Andrii Nakryiko
2023-11-03 0:08 ` [PATCH bpf-next 02/13] bpf: generalize is_scalar_branch_taken() logic Andrii Nakryiko
2023-11-03 0:13 ` Andrii Nakryiko
2023-11-03 16:47 ` Eduard Zingerman
2023-11-03 20:59 ` Andrii Nakryiko
2023-11-03 21:02 ` Andrii Nakryiko
2023-11-03 0:08 ` [PATCH bpf-next 03/13] bpf: enhance BPF_JEQ/BPF_JNE is_branch_taken logic Andrii Nakryiko
2023-11-03 17:28 ` Eduard Zingerman
2023-11-09 8:39 ` Shung-Hsi Yu
2023-11-03 0:08 ` [PATCH bpf-next 04/13] bpf: add register bounds sanity checks and sanitization Andrii Nakryiko
2023-11-03 2:13 ` Andrii Nakryiko
2023-11-03 17:56 ` Eduard Zingerman
2023-11-03 21:11 ` Andrii Nakryiko
2023-11-03 21:39 ` Eduard Zingerman
2023-11-09 8:30 ` Shung-Hsi Yu
2023-11-03 0:08 ` [PATCH bpf-next 05/13] bpf: remove redundant s{32,64} -> u{32,64} deduction logic Andrii Nakryiko
2023-11-03 22:16 ` Eduard Zingerman [this message]
2023-11-09 8:43 ` Shung-Hsi Yu
2023-11-03 0:08 ` [PATCH bpf-next 06/13] bpf: make __reg{32,64}_deduce_bounds logic more robust Andrii Nakryiko
2023-11-03 22:27 ` Eduard Zingerman
2023-11-09 9:02 ` Shung-Hsi Yu
2023-11-03 0:08 ` [PATCH bpf-next 07/13] selftests/bpf: BPF register range bounds tester Andrii Nakryiko
2023-11-03 19:19 ` Alexei Starovoitov
2023-11-03 21:12 ` Andrii Nakryiko
2023-11-03 0:08 ` [PATCH bpf-next 08/13] selftests/bpf: adjust OP_EQ/OP_NE handling to use subranges for branch taken Andrii Nakryiko
2023-11-03 0:08 ` [PATCH bpf-next 09/13] selftests/bpf: add range x range test to reg_bounds Andrii Nakryiko
2023-11-03 0:08 ` [PATCH bpf-next 10/13] selftests/bpf: add randomized reg_bounds tests Andrii Nakryiko
2023-11-03 0:08 ` [PATCH bpf-next 11/13] selftests/bpf: set BPF_F_TEST_SANITY_SCRIPT by default Andrii Nakryiko
2023-11-03 22:35 ` Eduard Zingerman
2023-11-03 0:08 ` [PATCH bpf-next 12/13] veristat: add ability to set BPF_F_TEST_SANITY_STRICT flag with -r flag Andrii Nakryiko
2023-11-03 0:08 ` [PATCH bpf-next 13/13] selftests/bpf: add iter test requiring range x range logic Andrii Nakryiko
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