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([2605:8d80:5825:58f:4756:80b5:ef0e:8463]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-829a4867e54sm11769815b3a.35.2026.03.09.18.30.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Mar 2026 18:30:52 -0700 (PDT) Message-ID: Subject: Re: [PATCH v2 bpf-next 1/2] bpf: Avoid one round of bounds deduction From: Eduard Zingerman To: Paul Chaignon , bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Harishankar Vishwanathan , Shung-Hsi Yu Date: Mon, 09 Mar 2026 18:30:50 -0700 In-Reply-To: <621f8a301a3a29af041ea8384ab09498e3f20322.camel@gmail.com> References: <5b8fed05cc97cd3730bbdfbb452699b7edd16963.1772840030.git.paul.chaignon@gmail.com> <621f8a301a3a29af041ea8384ab09498e3f20322.camel@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.2 (3.58.2-1.fc43) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2026-03-09 at 18:07 -0700, Eduard Zingerman wrote: [...] > Of-course, I might have some bugs in the test definition, but in case > the definition is correct, I think I'm inclined to agree with Ihor > here. If we can't mathematically prove that the sequence converges in > a fixed number of steps, putting a loop on top of it seem to be a > reasonable thing to do. >=20 > [1] https://github.com/eddyz87/bpf/tree/deduce-bounds-reshuffle > [2] https://github.com/eddyz87/deduce-bounds-verif >=20 > [...] Pushed an update to the test to check if new bounds are tighter than old bounds (instead of equivalent). Still get a failure log: $ ./parse-log.sh out2.log Values extracted from log: s32: [-1686110209, 1907957760] v_s32=3D-1411416065 u32: [ 1746894847, 4030210048] v_u32=3D2883551231 s64: [ -4350478693995380738, 2172132303447261182] v_s64=3D-43504786931= 50261249 u64: [ 2172132302103053322, 14096265381705949184] v_u64=3D140962653805= 59290367 Running C code directly: input: s32: [0x9b7fffff, 0x71b92000] [-1686110209, 1907957760] u32: [0x681f7fff, 0xf0382000] [1746894847, 4030210048] s64: [0xc39ffead797ffffe, 0x1e24f6d2501ffffe] [-4350478693995380738, 2172= 132303447261182] u64: [0x1e24f6d20001040a, 0xc39ffeadf0382000] [2172132302103053322, 14096= 265381705949184] old: s32: [0x9b7fffff, 0xf0382000] [-1686110209, -264757248] u32: [0x9b7fffff, 0xf0382000] [2608857087, 4030210048] s64: [0xc39ffead9b7fffff, 0xc39ffeadf0382000] [-4350478693424955393, -435= 0478692003602432] u64: [0xc39ffead9b7fffff, 0xc39ffeadf0382000] [14096265380284596223, 1409= 6265381705949184] new: s32: [0x9b7fffff, 0x71b92000] [-1686110209, 1907957760] u32: [0x797ffffe, 0xf0382000] [2038431742, 4030210048] s64: [0xc39ffead797ffffe, 0xc39ffeadf0382000] [-4350478693995380738, -435= 0478692003602432] u64: [0xc39ffead797ffffe, 0xc39ffeadf0382000] [14096265379714170878, 1409= 6265381705949184]