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 82F03EE4993 for ; Wed, 23 Aug 2023 16:45:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 04C9D28008E; Wed, 23 Aug 2023 12:45:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F3F4828008A; Wed, 23 Aug 2023 12:45:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E066528008E; Wed, 23 Aug 2023 12:45:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id D1DB228008A for ; Wed, 23 Aug 2023 12:45:30 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 9F69D4019F for ; Wed, 23 Aug 2023 16:45:30 +0000 (UTC) X-FDA: 81155945220.13.6F81863 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf01.hostedemail.com (Postfix) with ESMTP id F318340020 for ; Wed, 23 Aug 2023 16:45:27 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=none; spf=pass (imf01.hostedemail.com: domain of cmarinas@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=cmarinas@kernel.org; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none) ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1692809128; 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; bh=F3asxhugKBt55tUkNUwo5t1ThAN7aDBFkWK6hmuXBs4=; b=dyH2DPRkobAH47ZTdxAevdZIoMd6zcX8vLH0kdhFJ++qHyVhNg4HkbWjGz5iONBbVGjCfD 0Y3N2F4w19Kc97qaY6yHR90PLso5ueUeLIR2lt/k4FQHkoUMiYPO+NmvPaRZVYropjGS8O yHfpiWjtzJio2puR/rDDDvFOsfjjyq0= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=none; spf=pass (imf01.hostedemail.com: domain of cmarinas@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=cmarinas@kernel.org; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1692809128; a=rsa-sha256; cv=none; b=ukBprVaHoQ/xty1Ns2bymY5WcNG3DWrgyhATY8kRZboqTJprPpd75F6Az/tTbLIboTOcM0 b5m+5t0VmiFiD5fjoCwZ4n9TFT66yBP9Antdn5ZHSg1RR5yUqAvWMeQh69RdD55nKE+ev/ jogiye7bfWDWrSTqPDOeNMiah+drzjo= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C8D7C649D2; Wed, 23 Aug 2023 16:45:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 676D7C433C7; Wed, 23 Aug 2023 16:45:15 +0000 (UTC) Date: Wed, 23 Aug 2023 17:45:11 +0100 From: Catalin Marinas To: Mark Brown Cc: Szabolcs Nagy , Will Deacon , Jonathan Corbet , Andrew Morton , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Arnd Bergmann , Oleg Nesterov , Eric Biederman , Kees Cook , Shuah Khan , "Rick P. Edgecombe" , Deepak Gupta , Ard Biesheuvel , "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v4 03/36] arm64/gcs: Document the ABI for Guarded Control Stacks Message-ID: References: <20230807-arm64-gcs-v4-0-68cfa37f9069@kernel.org> <20230807-arm64-gcs-v4-3-68cfa37f9069@kernel.org> <43ec219d-bf20-47b8-a5f8-32bc3b64d487@sirena.org.uk> <227e6552-353c-40a9-86c1-280587a40e3c@sirena.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <227e6552-353c-40a9-86c1-280587a40e3c@sirena.org.uk> X-Rspamd-Queue-Id: F318340020 X-Rspam-User: X-Stat-Signature: cr8p4sde8ibg8gtaed1u1rgtjxg715k1 X-Rspamd-Server: rspam01 X-HE-Tag: 1692809127-757879 X-HE-Meta: U2FsdGVkX1/u5J/LBENMwWLDOaVrUXxbUkQxGTIzapzh586CcefhrrOqvRRYQAnqWnaqYuIwKOFWb3EmYipYNtQq2i2nje+tcgzmdGJvdLb1RP5Rsj+S4hzUehg3r6RDM/U6UWHUVC1V6mhMKKhOeN75kuW8oKEsjmVXeUiU38md0+OJaBStbvDENR7o2TtN3qiSyDPobEnZkqdhOAJRVZpFlvLekRzIikax/59lVapA/vtXCEmToSd2wc89evMl5X4MNp4yLKJncvmjci2alOV797cUhda2MAzEZ91/dNyJoT6lySpAFmHBUl5TBXOwzPs7fQ9Q/bOz6F1W7sm8PusfWcnDKAninaaKKhhUzceV1cAibxhZ3vz35QqsbBM5MyrPYINatU4ajASsVSet/8v84mnfBbe/G6UIlvZMeLZ4fVXhcREVSf6+lYKXBZJk+11FcKSuBCszN2NhCWhjhk3Odsdg7y1VLrQzdD5fBQ5Wcok5A5vVIERet0tWhOLhv1SRgISGZsr85AAZJMxVTwvPu7voVGLPyqgdowVuGppinAsbowWRkYdgGXLdnWQP32p6KYuB1gkZSCDWPJSmPWdjVgFCq13KcXq5qqz8AX6x6zX3pnNaPmii4phYz43twNCNXZfYIMnL7LsuzNx6FJcGukf07eMncoeraN0z1/fCaCy2oBpcclh4DV4DcgEMb07tEZZiclAQgm0P7WLHTBqFcvoYzCrvbw2S4BzDqKY5GU3YTCQYbTl+En/sw8ljWDeKSxz1RDO9YEQwdruAzZewfWwa/MfBrK1OOUajnwRpZu8iqPeaiTuOiFanMZUwY6/5Eyv8TJWpEQiuHmHq3Z4FAtAHIMHb8fwkFdj53A0zG9ce+uf9Xsn0FzV3A/nrAnrkYnQiVgZmPxV1kcdjMV8TqAVF0kQh33Dkp/RctIs2KfiYi+5YfQziGLjMzcoxY6j/J9OrpcNZA41R5Mi fM+ewwyU QO0ZXYXcRHbzMzGpxjye+eOBfKBiW8XRgGKR0m7C+yQMRkgChQVu5BfI4P7DEueYaqpq/egMl5sjPN4nMfMKUECIQhIaeBQr+ZsKEIDeyYiuOKvUAXlA3u8oVm4Z4nXnZErcZnzFNGo8CNEtw0VolUokNxII3SCG/z8MvlCgKcvyv4AjdZ626ZAFOdoKwExSM+Mb3325XI7xYtqsyqg+WKKhkYTBHKrAy/Jb5XOX83FVpqNMorN5ODcp9J+UDLTW1nE6/B6jMsxY3bgF9OZcPx06i74vL2fb/v4ahrW7bI2fEq7prwunooUyqaIKmisTOwA+XNc49nYArw4IIK0CCdOK4kW3+UnubZnnceJrzW6zOTC8Zbi+ftYvvwhk4yMIcPS78hM0UECuxeKG5GRD/rFBjNSHS4+Oo96m6i51Iq7Db2CKWYTQ9ijuObKgZKNYcUtjYNrav3JxFOYGct0oX3LMtHcR6IF2/oxZRnHa4FL+afcI= 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 Wed, Aug 23, 2023 at 01:51:35PM +0100, Mark Brown wrote: > On Wed, Aug 23, 2023 at 11:09:59AM +0100, Szabolcs Nagy wrote: > > The 08/22/2023 18:53, Mark Brown wrote: > > > My sense is that they deployment story is going to be smoother with > > > defaults being provided since it avoids dealing with the issue of what > > > to do if userspace creates a thread without a GCS in a GCS enabled > > > process but like I say I'd be totally happy to extend clone3(). I will > > > put some patches together for that (probably once the x86 stuff lands). > > > Given the size of this series it might be better split out for > > > manageability if nothing else. > > > i would make thread without gcs to implicitly disable gcs, since > > that's what's bw compat with clones outside of libc (the libc can > > guarantee gcs allocation when gcs is enabled). > > That'd create a pretty substantial divergence with the x86 patches if > they land this time around, there's not enough time to rework them now - > I suppose it'd mainly bite people implementing libc type stuff but > still, doesn't feel great. I don't mind the divergence in this area if the libc folks are ok with it. x86 can eventually use the clone3() interface if they want more flexibility, they'll just have to continue supporting the old one. I think we already diverge around the prctl(). -- Catalin