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 ACD99CA5FAC for ; Tue, 20 Jan 2026 16:37:54 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4dwY0K1rrwz2xQB; Wed, 21 Jan 2026 03:37:53 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=192.198.163.19 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1768927073; cv=none; b=Q4NYkesxHVeuRO5f8IUiPoRLCVbNVp2jvHwWT88nX8FCJyYQ3etYaGggRWqTGY7rPk843wHbZouwbBWZYmYuZu8QIBrELfoxOiWXRErhYuKI54MiHABUyDbE74LLzGIZBB6uV8XVl1Jc0H8oS1cJ7mAVHyIIOEnVkd3wskz6hNqfwTN64uXkD3Tf9fDLKGV9BSV2eFcaHYoCgwrCgCSCET2shJpbGN5R7ZMRQzi1b9pbNWNd1MS9cdLw+56rFMFdqGmDSqbUiwDyYKsjxPB2jd0eLHzLMdiZ/lIc02EhGkrTR/Ug2flTRaDlm1iMGs1QAhWyoGV63c+PLLtz0WNkPg== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1768927073; c=relaxed/relaxed; bh=l6zt9Aq16n1bm0FvTo8vindZbxHrJGqWuAngHOx6RHU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WTIKkQA8NTmtkcAXpW4FpE+3QMfswGBwzUevC6YzXZ+vK6v6UgQWbz5YO7ZRetRFz1NfBZd9dU6/nmP45duOEwh7zNEJX8MI7dg/b/792agxixxBrJ5xHEs+iagnR6gebqdzQuwdMXVLCopGJPEEPQ2hSXqLwTTetnhsmmZK43O1bJfFHgEqO7VW1Zn14LGvCQyFcnjaZETjAEV5IaE5x5OmRb4HB8r3EwIDqIcONmA/fiwr7y8Jt6Uttnbygj7ClhD5VtZxkRgTljynqO/oDvPQ4/EkWXsPh2TZPlWjNTGM4yenuq46Ltlb+INDtZDg6SMo+pfgr4Z0EGlLIJi+3Q== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=intel.com; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=ER76PCn3; dkim-atps=neutral; spf=pass (client-ip=192.198.163.19; helo=mgamail.intel.com; envelope-from=dave.hansen@intel.com; receiver=lists.ozlabs.org) smtp.mailfrom=intel.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=ER76PCn3; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=intel.com (client-ip=192.198.163.19; helo=mgamail.intel.com; envelope-from=dave.hansen@intel.com; receiver=lists.ozlabs.org) Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4dwY0G5mzwz2x9M for ; Wed, 21 Jan 2026 03:37:49 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1768927071; x=1800463071; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=l6zt9Aq16n1bm0FvTo8vindZbxHrJGqWuAngHOx6RHU=; b=ER76PCn3lwV16gz2IP/oTFD7qNTHsPeR/E/D3Zi2i+vcYZg28aIJeihc /IGBiVWeDqNvBK4c6hvkDURMaPhb9RoP2LZTXf/WYLiLTjvbZNolHTq47 TPPNUQpGW6bpSxAEIKMkImk5DpzHMaFbe7Qm6SA6ynyxexUDfQUiOQRyD q7STRfsH5Z9JfNMScliO7uFe2jdtGAYjpoM0lEjV9p0gQEx7wAg49lhzT FJfVkWvuhJR6th+jtLyYH0yzZ/zN5vwxuNvgsoSUPW1t5jCpnEKuo1J0M X4ClYg0uxTJ3j03p0+qeNQ4H63UwiUp0J0aKr1sKaEGxNr14slfC/vQ3D Q==; X-CSE-ConnectionGUID: 1ImNIayuQBen9eVettn3CA== X-CSE-MsgGUID: frrQwot0SLWKAZOT0pctfg== X-IronPort-AV: E=McAfee;i="6800,10657,11677"; a="69156593" X-IronPort-AV: E=Sophos;i="6.21,241,1763452800"; d="scan'208";a="69156593" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jan 2026 08:37:46 -0800 X-CSE-ConnectionGUID: i8YmVT04SAqzglnbuUMMhg== X-CSE-MsgGUID: ukbzNSMQRBCd4IS3CMSH7Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,241,1763452800"; d="scan'208";a="206422303" Received: from vverma7-desk1.amr.corp.intel.com (HELO [10.125.108.22]) ([10.125.108.22]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jan 2026 08:37:44 -0800 Message-ID: Date: Tue, 20 Jan 2026 08:37:43 -0800 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 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 0/3] Fix bugs and performance of kstack offset randomisation To: Ryan Roberts , Kees Cook , 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 References: <20260119130122.1283821-1-ryan.roberts@arm.com> <20fb97f1-7e50-485a-bdfd-a2901d20ec84@intel.com> <785a7d90-babe-43af-93a6-c220c1877bcf@arm.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: <785a7d90-babe-43af-93a6-c220c1877bcf@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 1/20/26 08:32, Ryan Roberts wrote: > I don't think this question was really addressed to me, but I'll give my opinion > anyway; I agree it's pretty binary - it will either work or it will explode. > I've tested on arm64 and x86_64 so I have high confidence that it works. If you > get it into -next ASAP it has 3 weeks to soak before the merge window opens > right? (Linus said he would do an -rc8 this cycle). That feels like enough time > to me. But it's your tree 😉 First of all, thank you for testing it on x86! Having that one data point where it helped performance is super valuable. I'm more worried that it's going to regress performance somewhere and then it's going to be a pain to back out. I'm not super worried about functional regressions.