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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0469BC282DE for ; Fri, 7 Mar 2025 22:47:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F2D476B0085; Fri, 7 Mar 2025 17:47:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EDC696B0088; Fri, 7 Mar 2025 17:47:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DA51F6B0089; Fri, 7 Mar 2025 17:47:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id BF5546B0085 for ; Fri, 7 Mar 2025 17:47:18 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 011FC1210FB for ; Fri, 7 Mar 2025 22:47:19 +0000 (UTC) X-FDA: 83196242640.18.FB5409B Received: from mail.alien8.de (mail.alien8.de [65.109.113.108]) by imf28.hostedemail.com (Postfix) with ESMTP id AE636C0006 for ; Fri, 7 Mar 2025 22:47:17 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=alien8.de header.s=alien8 header.b=ZybLeiGE; dmarc=pass (policy=none) header.from=alien8.de; spf=pass (imf28.hostedemail.com: domain of bp@alien8.de designates 65.109.113.108 as permitted sender) smtp.mailfrom=bp@alien8.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1741387638; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=hUu5/rpMox0T3Vcm+1lPtdALgmUeb93/9iSEx9fEkY4=; b=2Go+68Yz5OjFLGemB8QWXay5HTqvfpuxwyjY6u1D9Ypkqd1Ww5bovTAIcrkZ220d4AZgSa aECl96y8kskyFyPXIwX49abAW9voAF1tjJ6emh2MfN6I5PXQilfpuZ0GcOyz4S2lFtZoRd ojgSTvFo/04wGsFAcjanoMGd/CWOUQ8= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1741387638; a=rsa-sha256; cv=none; b=UjT+K9/ZYf3Q8JV13SXjHK/64nXgHWDlrVM3M5j6/Y3XElwhDpPj0tDckyxPi7SEMlFBus ApH/NC/QVJh2Gr1Ult0lyrniUh2R4yk0gDhE5JWf7T0J4360uItVQq1BQbWVA9ae6ZbW5u ANcXNz+Bt9hHW7XfLzO98fs114HcOh8= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=alien8.de header.s=alien8 header.b=ZybLeiGE; dmarc=pass (policy=none) header.from=alien8.de; spf=pass (imf28.hostedemail.com: domain of bp@alien8.de designates 65.109.113.108 as permitted sender) smtp.mailfrom=bp@alien8.de Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTP id 7928940E0214; Fri, 7 Mar 2025 22:47:14 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mail.alien8.de Received: from mail.alien8.de ([127.0.0.1]) by localhost (mail.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id eNGvWaWz9nat; Fri, 7 Mar 2025 22:47:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=alien8; t=1741387631; bh=hUu5/rpMox0T3Vcm+1lPtdALgmUeb93/9iSEx9fEkY4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZybLeiGEw0Hb+BRvk7jZ3m46EniCvZMNqQNelPB+hkkKltOCz3zBNy2WTYwR7eO6l ufCAb22jgVbfC/9x31DbnQaCELgtqGGlZMEkP2soiyOyZsgHiEGgPJNH42zCTMT3zv nsoVMC1KdL9KCjvDuGwpR+NnVQpjZCuWAFL1cxpKCkqKTy6Rt39/o/UiqoD1IxHSVF H/HdyyVrw1u04MRYiDzIuHEZa0BFzraIrxQD5c4ayWPD2/mR992ChWziYuqo/ZuG88 xHiATgb9w3hKIy8Ibdov5MBuYtTjU0GuiW/cdHtXQwLwNou/25vLlmJlOSMgBugmzV Fje5aIQnw8JZ3K4p51IcZqtq5cAadjvwfUwmmkzUW93G1uNpfPs0xP5e0M7w4xfFwU hK912nyLouM8pgPTihrtN0JsV8ut0kTTCmiJxi9Aj+Tq+GR31asnuEEdshZOSy1uk8 muVZiVkZprEH4bkWPVm1hAM9d9pHi/OHcAGxZXfbCiV3a8l4cR9i2FrkX+HSslSwS7 ZlwFFPDhTILTT+jwlzlatf7tm1jjleV+n+7I62kEOo8Yl7LMlM11zrQ59IvyaElMUy RG/q4vbLFSudiwuDmHlNu7Nh1FJqMcp7JuAgxIQA+6tl39KNNSzNMVWqOZ1YXVCS59 0VnqeOLkhuxQqFn3+diETrDc= Received: from zn.tnic (pd95303ce.dip0.t-ipconnect.de [217.83.3.206]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id A552540E015D; Fri, 7 Mar 2025 22:46:51 +0000 (UTC) Date: Fri, 7 Mar 2025 23:46:45 +0100 From: Borislav Petkov To: "Luck, Tony" Cc: Shuai Xue , "peterz@infradead.org" , "catalin.marinas@arm.com" , "yazen.ghannam@amd.com" , "akpm@linux-foundation.org" , "linmiaohe@huawei.com" , "nao.horiguchi@gmail.com" , "tglx@linutronix.de" , "mingo@redhat.com" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "jpoimboe@kernel.org" , "linux-edac@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "baolin.wang@linux.alibaba.com" , "tianruidong@linux.alibaba.com" Subject: Re: [PATCH v4 1/3] x86/mce: Use is_copy_from_user() to determine copy-from-user context Message-ID: <20250307224645.GKZ8t3VX5a5FhqNyZG@fat_crate.local> References: <20250307054404.73877-1-xueshuai@linux.alibaba.com> <20250307054404.73877-2-xueshuai@linux.alibaba.com> <20250307204018.GAZ8tZstt11Y4KFprC@fat_crate.local> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Stat-Signature: ubpjt6qpzqcw5pghwd9iqunsy3tm4c9r X-Rspam-User: X-Rspamd-Queue-Id: AE636C0006 X-Rspamd-Server: rspam04 X-HE-Tag: 1741387637-848989 X-HE-Meta: U2FsdGVkX1++JmBIkQFYER/k5lwFVK6wUNr8l87GRPXTQji3K3p2vEiimVupjfkkF02aF5qtXIRWtBN9bnMSJI9qYZcLbBLhNu5CluSBYNZW33LS/4bojQUB0LWWuhzIPj5seJysOMkul+SXX4/YIHzIJFBQOmzev0R5zpt/wphQKaGipKmeP4LsEYPazEFfB+woKQqscCpiPtutR6osHzzWWe3o+LWfeMxtfk2Iu+6KSh4Z1Q0OL7Byj6z3bzsh0qxbM7kADi29ekGKcNocbYryampzuywmlTX7ab6gKXhQ8rvfSLutkFsif2jBSTi0i5gvD7olIJuJ0W2jQBnXk9uM2uEiqSImiR85Gp3HAlIFUOurYOYqYgeo8NB88akZbLmBbTEhAxH1XExvDcYdMM+ET4LDwiloPf+6eWoajaxMSUwqyydGwk5VBZc2vkV6bqQn8tRLCfnjqZfm0E/7vgY/Svj2v/nVGa2rEH0iTSgglcFptJYwYterqXUPn1nIUL+MoROIxjAZZ79WOzNqdAU6ZCTWSR8zJx5qTFbha0NhKe2HBHHsHEVzR9h0bvAw2H3YuVRX9bXWSvlODi4NEwaxUTYihWSCWDJZg6QIfEcYazDBC8512Y746LCYCQD1oFu71HiC5NQjNqA1O2Sr0UO8JpKx+9r22XUaDCDKDXH2DWpKzg/QvZwa+LhZUyhfmFG7TOWNvT0F1gV2I4YXy7w2zcveawVcclDuXS0cHxMPq43M9dRVE8H298viU1kCVFyHuB/XnKVJWRNhm3tpiEJhSx8OiJzI0tIXXMaHaqRvnA5m6j7x8xULfHPG/urTpl7MQ87iJnb/UkfyZmDCLxIqmkOpgQJqIUkw6dQ/dbOysDHjGaRMZNOoCbUwFELFsNOe518iY6e2nIQBULtFrCp/rVsOKi6q63a5LIhV6RLtDdQITI2eD6Yf/lA2rTXjdQYpAwDQBQVdYTolsT/ avncTt/M CVJZ9A7o9fPuZNi6gMaxV8vMSFmk8G0Ppnd0cahfihck3joSKdRta3cyJDry5NDv6Fgi5EvoeoOwoF55mkS6ZdonFSlNu26IgIMSpVzKG7Fo2HnfF1YrCjTH2nr0uXouqFu/goNlWKmEvNGB6ujpoZK5Y89WIeFRQOqjOl76mU1IC7bMTrFnZQrEJ2rx334Ba8gM8v5w1IAY6n0NUkFDKC7u9ITf9N4bCMAXHNRlB6vZ5NNhzQ01MmKnNsGwwW7JUyGhyZs63f1cJxYjLU59wy6MX25Z5xVyLzs+yizTNAVgpJcH16OxTqNTYKvMZ7jj9Vkb1soy0fZTc5ZR4rAz47gkYF5TB9PWnXIEyHZePdpY49li0kQpU/PTmctIZQPy6c7iMhzf5rIPIKZocOQqcMEJy7h/84nFreikGc/+uh2mzGskEIr6IYgc8EA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.210863, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Mar 07, 2025 at 10:05:12PM +0000, Luck, Tony wrote: > is_copy_from_user() decodes the instruction that took the trap. It looks for > MOV, MOVZ and MOVS instructions to find the source address, and then > checks whether that's user (< TASK_SIZE_MAX) or kernel. You mean there's absolutely nothing else like, say, some epbf or some other hackery we tend to do in the kernel (or we will do in the future) which won't create the exact same two conditions: - one of the three insns - user mem read and it would cause a recovery action. Perhaps it still might be the proper thing to do even then but it does sound fishy and unclean to me. Nothing beats the explicit markup we had until recently... -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette