From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 32BB4314A95; Mon, 19 Jan 2026 16:44:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768841060; cv=none; b=bvSJ/KszOCdT6r8ICJEDnEso3ReKZ7lg+aYHi8gIdgZUXz0i4LGT384+CtD6achCkQZ++wdCBeBc4gz42TfSwoltxvkQmnkuDCJmbsmYDnPLIR4/fdl8OU6pzSgLQcbqHPXe7mfcloop1Th24NU50ETFODMyqyOBds8S2kIefKw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768841060; c=relaxed/simple; bh=16FGOoiet4+IrVT+FcqrHcvY6YUTC0QcugfuzrxpDdk=; h=Date:From:To:CC:Subject:In-Reply-To:References:Message-ID: MIME-Version:Content-Type; b=lhwdOT42hY318Mb87rgRlbHXno6nkfKSYUCCBv6nsYsgVVg+KzaPLURLLgblRa0hf2Zi/JxeFTzro6KdgDFMCobjXllY5y3FpTY3uwmqTMjjmVnCtc4fegHzs+ixuZVS/EX6jkGMsGaloAIzQUw15WRj1SLOzGMluiCbr1MAtYg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=q0tAOJQS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="q0tAOJQS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B80FAC116C6; Mon, 19 Jan 2026 16:44:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768841059; bh=16FGOoiet4+IrVT+FcqrHcvY6YUTC0QcugfuzrxpDdk=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=q0tAOJQSpR4lAPo9D9a0ZLzj9fmk4VEFSuwyHRGgr6m2/2bnlj2msqm1OK35ZA72i BsoEW2Hi1Kd0mpXDYPCuFTDERjp9sFatntALxM7RaexoblAcWHEgiVDgn5GR/Cfhs5 lJ+7nmPuUhjsYr7LMg0JLovICzoM9fTlHD0eazCWxNpHY+vxS6kc8rz0ZKG0d1VEWg IIhlCXiVHIe0pBTCOoVEENtJxJ+QEakuwJKi7yA2fm+eSBFbxX2gEsdDI8+DoA1Vyk WSTb5IyXokPQcIaRg69SRVfbN0PLcfWUE2soFEJxCYrdO9X8LHmJmpvUejzzI3uzi8 2/W6/Js/SDGRw== Date: Mon, 19 Jan 2026 08:44:17 -0800 From: Kees Cook To: Dave Hansen , Ryan Roberts , Catalin Marinas , Will Deacon , Huacai Chen , Madhavan Srinivasan , Michael Ellerman , Paul Walmsley , Palmer Dabbelt , Albert Ou , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "Gustavo A. R. Silva" , Arnd Bergmann , Mark Rutland , "Jason A. Donenfeld" , Ard Biesheuvel , Jeremy Linton , David Laight CC: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-hardening@vger.kernel.org Subject: =?US-ASCII?Q?Re=3A_=5BPATCH_v4_0/3=5D_Fix_bugs_and_perfo?= =?US-ASCII?Q?rmance_of_kstack_offset_randomisation?= User-Agent: K-9 Mail for Android In-Reply-To: <20fb97f1-7e50-485a-bdfd-a2901d20ec84@intel.com> References: <20260119130122.1283821-1-ryan.roberts@arm.com> <20fb97f1-7e50-485a-bdfd-a2901d20ec84@intel.com> Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On January 19, 2026 8:00:00 AM PST, Dave Hansen wrote: >On 1/19/26 05:01, Ryan Roberts wrote: >> x86 (AWS Sapphire Rapids): >> +-----------------+--------------+-------------+---------------+ >> | Benchmark | Result Class | v6=2E18-rc5 | per-task-prng | >> | | | rndstack-on | | >> | | | | | >> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D+=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D+=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D+=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D+ >> | syscall/getpid | mean (ns) | (R) 13=2E32% | (R) 4=2E60% | >> | | p99 (ns) | (R) 13=2E38% | (R) 18=2E08% | >> | | p99=2E9 (ns) | 16=2E26% | (R) 19=2E38% | > >Like you noted, this is surprising=2E This would be a good thing to make >sure it goes in very early after -rc1 and gets plenty of wide testing=2E Right, we are pretty late in the dev cycle (rc6)=2E It would be prudent to= get this into -next after the coming rc1 (1 month from now)=2E On the other hand, the changes are pretty "binary" in the sense that mista= kes should be VERY visible right away=2E Would it be better to take this in= to -next immediately instead? >But I don't see any problems with the approach, and the move to common >code looks like a big win as well: Agreed; I think it's looking great=2E --=20 Kees Cook