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Tue, 9 Jun 2026 18:58:10 +0000 (GMT) Message-ID: Date: Tue, 9 Jun 2026 14:58:09 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] crypto: ecc - Optimize vli additive operations using compiler builtins To: Fabian Blatter , lukas@wunner.de, ignat@linux.win, herbert@gondor.apana.org.au, davem@davemloft.net Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260607112435.42804-1-fabianblatter09@gmail.com> Content-Language: en-US From: Stefan Berger In-Reply-To: <20260607112435.42804-1-fabianblatter09@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=b4uCJNGx c=1 sm=1 tr=0 ts=6a286245 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=RTuf3evP9GeFNN_N0Y0A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: TkO3KmtKbF4ZAskeUAwkAe63D3qo4pTt X-Proofpoint-GUID: 1CL4EIcqlM8b5JFwtL_keCGzIG7DDq6D X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjA5MDE3NSBTYWx0ZWRfX6Z+ry4KU5H46 k7+QV8nJwc8I1gRSFi7PpsioJk4EtobRPb1ienuqHEI0trxLMWjLJgrXggkbPDicJH2cBExsSqX GNmamQkEZOxii4hSM4fUaKSYC7Ilhhg50gqovRO5GfMS6CcPa4abejzfZ93L8GXltks1jrSY/n0 sC6EqSlsw/owfEKUGfrEWJVMbaAWPzRNqFF7tVGns7zs6KI6JtbYPKi3vGKN8A2YedsQZz3drmk GRvDiMi7GFoLnd2AW13TE8ah6l8EAkUExsyOo5AyLYvwM498uFuncOcZt4L9W5Kx1U9nXCY1ReB gwLAbXpsOshkp65mb5ep4F5ZeaN8lKXiBykSfavq59ZPzmetZ1hOAmUgvgL6qKpQ8R+9iL2Y571 VFxApDpeT3190TxqCLW51ypF5sSGjHy70nTkRjpUN9kysb8P8hrdYpyZdmdEWXpi6nym1368J3n yapojNdXz0LdBgTeJ2w== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-09_04,2026-06-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 spamscore=0 bulkscore=0 phishscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 malwarescore=0 impostorscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606090175 On 6/7/26 7:24 AM, Fabian Blatter wrote: > Replace the software carry flag emulation with compiler builtins. > > Even the newest compilers struggle with taking advantage of the > hardware carry flag. Compiler builtins allow the compiler to > much more easily achieve this while still remaining constant-time. It looks like you made vli_usub and vli_uadd constant-time now because otherwise the loops could be ended early once borrow == 0 or carry == 0 respectively. Are all the other functions that operate on the private keys constant-time?