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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D0BA3C433DB for ; Wed, 10 Mar 2021 23:56:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4C08464FA9 for ; Wed, 10 Mar 2021 23:56:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C08464FA9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 41A8D8D0252; Wed, 10 Mar 2021 18:56:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3CA428D0250; Wed, 10 Mar 2021 18:56:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B9208D0252; Wed, 10 Mar 2021 18:56:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0088.hostedemail.com [216.40.44.88]) by kanga.kvack.org (Postfix) with ESMTP id 108D38D0250 for ; Wed, 10 Mar 2021 18:56:06 -0500 (EST) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id C3D32181AF5C4 for ; Wed, 10 Mar 2021 23:56:05 +0000 (UTC) X-FDA: 77905625490.28.AD4936B Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf20.hostedemail.com (Postfix) with ESMTP id 8BAD213A for ; Wed, 10 Mar 2021 23:56:01 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 189DF64FC5; Wed, 10 Mar 2021 23:56:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1615420564; bh=UVXuRCiWw34IqJcMP9Uv9Jas9cv4G39lAIuBiEicriY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=emLhvYekhyBaZ2AfJJbUlNuRJXxCMIRvvMmTGCMfmtu3W4qCwgfn4RGHsYAbmvtml Fupl3RPBbQ9Wx7pIbmVfJT+Tavgxx7GGU17KfvQKSGsA5QPUffBps21tzjTWiNUUnC eA9ut0KtOpOisfHMMlTqywPwMQWyn8dim1tOd3TE= Date: Wed, 10 Mar 2021 15:56:02 -0800 From: Andrew Morton To: Kees Cook Cc: Thomas Gleixner , stable@vger.kernel.org, Elena Reshetova , x86@kernel.org, Andy Lutomirski , Peter Zijlstra , Catalin Marinas , Will Deacon , Mark Rutland , Alexander Potapenko , Alexander Popov , Ard Biesheuvel , Jann Horn , kernel-hardening@lists.openwall.com, linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , David Hildenbrand , Mike Rapoport , Jonathan Corbet , Randy Dunlap Subject: Re: [PATCH v5 1/7] mm: Restore init_on_* static branch defaults Message-Id: <20210310155602.e005171dbecbc0be442f8aad@linux-foundation.org> In-Reply-To: <20210309214301.678739-2-keescook@chromium.org> References: <20210309214301.678739-1-keescook@chromium.org> <20210309214301.678739-2-keescook@chromium.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: nbcr5fgbra9ofii78tak45o8z8yd9aih X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 8BAD213A Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf20; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615420561-365225 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, 9 Mar 2021 13:42:55 -0800 Kees Cook wrote: > Choosing the initial state of static branches changes the assembly layout > (if the condition is expected to be likely, inline, or unlikely, out of > line via a jump). The _TRUE/_FALSE defines for CONFIG_INIT_ON_*_DEFAULT_ON > were accidentally removed. These need to stay so that the CONFIG controls > the pessimization of the resulting static branch NOP/JMP locations. Changelog doesn't really explain why anyone would want to apply this patch. This is especially important for -stable patches. IOW, what is the user visible effect of the bug?