From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5AA59D29C40 for ; Mon, 19 Jan 2026 16:44:24 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4dvxBG6DTDz2xjb; Tue, 20 Jan 2026 03:44:22 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip="2600:3c04:e001:324:0:1991:8:25" ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1768841062; cv=none; b=fQfEYSX9Uj5OhOqxkj5RA+cQFFptzoCe8V4b4Z4n302BKuBlADJD2NSubNILXuTjMtNlYKKfMBgb8Ik9IHQtF5smOCkKKLJdQJf84cW6GbIvtMPoYh64VyYJvdruvG+mzNy1/KAAInxOSxLmBuB2lxQaW0baoT0330ojI2TuInOmUvDwW01+AGtDausfPoCqbZeabA6Pdl3olE0pzs9xg62VS6GmKl+5P9T7w+to/sxRhsRgiDyDNy9TjgBMvXvXehef4EOu1Sdq744knJ/zLF/+LxpH4D0HV50F4gD8DPGyArefTTiKFrdbQ0bp9Y3x4xA9hHVSPzWHmlRGwjEOQQ== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1768841062; c=relaxed/relaxed; bh=Uw6KihBC1TRdvi5ZGo68c20jmI6Js3ekwsf6FSSvJdY=; h=Date:From:To:CC:Subject:In-Reply-To:References:Message-ID: MIME-Version:Content-Type; b=b/eKxjZuDWbVYbW1ibOZywCogoIc4sVOyOqEjcW/qO/suqCTunyl9DPZ3dtPEHbZTE96xrmUvSZW1Bvz7pi/JQTn4MF+HvtJYabzrV+fd5N+S0n9xq4/HsZqRHCOe3Zj3N6rT5+fIg+wPCx0RUVCXE/1exqTMfZn6rf+nUtIsNT//MCThq36YPWbtJwirL0Z9rtsi3TkE80+8la5j/0LMTLa7tvByeWm8ZNAQzQ2saRtG5ewLfCTzbmRKc7uh3DfW1WxknWZK6yCUrl13JSIAgEc6LB6orRUNQaPhfi6/1zcnrt1RBD0MoiYHy7fiUQTCxjAEYTWgwJZ/orJHzOBvw== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=q0tAOJQS; dkim-atps=neutral; spf=pass (client-ip=2600:3c04:e001:324:0:1991:8:25; helo=tor.source.kernel.org; envelope-from=kees@kernel.org; receiver=lists.ozlabs.org) smtp.mailfrom=kernel.org Authentication-Results: lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=q0tAOJQS; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2600:3c04:e001:324:0:1991:8:25; helo=tor.source.kernel.org; envelope-from=kees@kernel.org; receiver=lists.ozlabs.org) Received: from tor.source.kernel.org (tor.source.kernel.org [IPv6:2600:3c04:e001:324:0:1991:8:25]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4dvxBG05PMz2xS5 for ; Tue, 20 Jan 2026 03:44:22 +1100 (AEDT) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 22A0760054; Mon, 19 Jan 2026 16:44:20 +0000 (UTC) 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: X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list 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