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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 6DC74D11715 for ; Tue, 2 Dec 2025 16:59:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=NVDDeDsI7voWK2iMpphDuZXy8UNo3zOmfcXW7ODA8PQ=; b=TZuyuW2YdQ4IE7Fh7nInPIKPxY 9cW40ad1Win3d685z/h/RrsJnd/qud7kMB/QKkO1wubq+aJXGmRJd/KI8ZGKHyLbOmLGM7BZoX+S2 7HhyF++HGzGUnDF+SricLmKiS4cMFcOp4R/u0rN7HIIP8GbsJhKVDLAi7JRi5Sdc7lub2S1+5K+61 pD8p/SL4j2tOhJ2rDQutvpsFwpe7utUfw3m2ZEE7Xj+4cmOyu6RMK6PXqVt+IjnnKR65RodsfX/7o JIY5NL2Wex0T/hLZ2Z6ghxnrel6SG4BiPuwp7v6BIaU4X1y/7hs3sMCaBo7fRY6/mS8/IY7x/shIt 4IwUMY2A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vQTiZ-00000005e5x-0s0A; Tue, 02 Dec 2025 16:59:11 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vQTiW-00000005e50-44sH for linux-arm-kernel@lists.infradead.org; Tue, 02 Dec 2025 16:59:10 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id D103441973; Tue, 2 Dec 2025 16:59:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AFA00C4CEF1; Tue, 2 Dec 2025 16:59:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764694747; bh=BKuRmo/5X5VVzMCwr0RNY84CwTP4HWe2icEbznJHVzc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YKAi/mUAqSC/tVRSdbcmC8qjlezFOCw66U60BYYB54O8IHOMfIELqMmRm/3DgO30N jXu7BmHni2QysJ+encGdMUd2U11R5r2u7gCtWvZBBzjDO//T/zVij8Cnpha6MQ1fhJ zbkJf8+kEILwxG3D1lWhiIXXYOiIkix7mbCFNlGSfG5lCJqTf01zSQrJt5CW27paFu mYwt3ztzKiaKc+3bttfcOz9B3Bv8xA5W0s3HlITnSCpgjtymU3btwcrQq+BPLek8jA jlaKIRNXFH2V0mEITs0MuHOLE92cvn39QfC22BSjE/rbB00WQXapE642ZijCDvfOsX 9Jv1TTBTDbjxg== Date: Tue, 2 Dec 2025 08:59:07 -0800 From: Kees Cook To: Ryan Roberts Cc: Ard Biesheuvel , Will Deacon , Arnd Bergmann , Jeremy Linton , Catalin Marinas , Mark Rutland , "Jason A . Donenfeld" , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v1 0/2] Fix bugs and performance of kstack offset randomisation Message-ID: <202512020858.8BD22F486@keescook> References: <20251127105958.2427758-1-ryan.roberts@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251127105958.2427758-1-ryan.roberts@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251202_085909_029039_5D56B414 X-CRM114-Status: GOOD ( 10.75 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Nov 27, 2025 at 10:59:54AM +0000, Ryan Roberts wrote: > As I reported at [1], kstack offset randomisation suffers from a couple of bugs > and, on arm64 at least, the performance is poor. This series attempts to fix > both; patch 1 provides back-portable fixes for the functional bugs. Patch 2 > proposes a performance improvement approach. Just to chime in -- this looks really good to me! Universally improved performance, reduced complexity, and better randomness. :) I'm looking forward to v2! -Kees -- Kees Cook