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 4AB43D2F7CE for ; Thu, 17 Oct 2024 12:05:51 +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:MIME-Version: Content-Transfer-Encoding:Content-Type:References:In-Reply-To:Date:Cc:To:From :Subject:Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=YSnSp0r4RqmfOCJ1eCsDm0DfkQki2jgFL8MrJv2HVr8=; b=2+4bWdzhnXSVRhuv6z6HMZDBff x845W/IV/nmc+EIFhV+D4Ysf2o756N3l7biBU8ilNRy0pPh1Hm7ZQfrwwQF3LLuf6Yadd0LrYywHg b5Cy+0rU9WT3CVv/8YPxRNvOX2kh7BprkdVhJo7YqX3BKuW63sCvV2lib0RKwAm4W1Qk9lO8InZAZ BDukaUKnn4QpkZh9RpwGZMYeULjyEhFTn2s2rMqXZJXDvLJXpDljLFaZaUk0W7S+Q3r+he1KovzXd R5msb64jABr85d2mAWD/pNlb2Lea79zrRpHALqSKyFkJE0kCYWe/Npgk20gdUdD7NW6sNSMfIvIni wrAOe+Zw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t1PGI-0000000EiwN-1ERt; Thu, 17 Oct 2024 12:05:50 +0000 Received: from s3.sipsolutions.net ([2a01:4f8:242:246e::2] helo=sipsolutions.net) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1t1PGC-0000000EivY-13zL for linux-um@lists.infradead.org; Thu, 17 Oct 2024 12:05:48 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=YSnSp0r4RqmfOCJ1eCsDm0DfkQki2jgFL8MrJv2HVr8=; t=1729166743; x=1730376343; b=EKulbi5+XTBx1uJ7JWGlkXiCDIDiVH+mK1O3YlhipL5ERLj UvaUT/E0o612FiVQgW8F89r3DatbBryuCLUHjGlnHSs49aYemoDQx5s7QMh26in8/FbWcegnJvdNR Qt2jj9Z7msY4yp7ZEOm32TCSeOrkkpAFsJPUKldX7VBPb9AFLlRHmg+vC/QvP5H8xKWVSQ4s81+JU hPz+qK2I1gZ7q+hHTSdmVcIMnKKy3ooXFq/aBeA66/JCUuiGor6j605IVRBVNPuX7YwEUvNDNkzJz r11qjfFC/wR81b+veFf5oyQ+3O16ZOiEb1nIpxsPOK1s2e+JTSScjX7hDjPIBVUw==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.98) (envelope-from ) id 1t1PG7-0000000DuXK-3IPN; Thu, 17 Oct 2024 14:05:40 +0200 Message-ID: <9b9b26965e8ca5cdf9b05b5d56a418a2941fff42.camel@sipsolutions.net> Subject: Re: [PATCH v9 02/10] um: use execveat to create userspace MMs From: Benjamin Berg To: Johannes Berg , David Gow Cc: linux-um@lists.infradead.org, KUnit Development , Kees Cook Date: Thu, 17 Oct 2024 14:05:36 +0200 In-Reply-To: <49ef8267b4c2cbce11698a377330d92327b332d3.camel@sipsolutions.net> References: <20240919124511.282088-1-benjamin@sipsolutions.net> <20240919124511.282088-3-benjamin@sipsolutions.net> <49ef8267b4c2cbce11698a377330d92327b332d3.camel@sipsolutions.net> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.52.4 (3.52.4-1.fc40) MIME-Version: 1.0 X-malware-bazaar: not-scanned X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241017_050544_313555_59C9D4A9 X-CRM114-Status: UNSURE ( 9.70 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-um@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-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org Hi, On Thu, 2024-10-17 at 10:18 +0200, Johannes Berg wrote: > [SNIP] >=20 > I wonder now if the SSE instructions generated are memset() and that > goes away with the patches that Nathan just sent to not have the memset > (which was due to -ftrivial-auto-var-init) in the first place? I am guessing it would not fix it. I can reproduce the problem if I add __attribute__((aligned(16))) to the "stack" variable. That is sufficient for GCC to emit an offending movaps instruction for me. The -ftrivial-auto-var-init=3D option will not affect that initialization. > But anyway all of these pretty much sound reasonable. We don't need much > to happen in the stub here, simpler is better. Yeah, and I guess c) really is sufficient by itself. Benjamin