From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from GVXPR05CU001.outbound.protection.outlook.com (mail-swedencentralazon11013048.outbound.protection.outlook.com [52.101.83.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 67C914B0CA3 for ; Thu, 1 Oct 2026 09:01:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.83.48 ARC-Seal:i=3; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790845314; cv=fail; b=u60imJ9obRlG/QyejABamUVLJCnBiZSYSMIlVxFzRAco4VFHVPYsO2xBcvTqzSafhizJCVeSgrgBHsUpw8Or+2lnoYF0E+BwJK5Z1VbadrX8fW4YGvA+Qa2eVtYeISql71VFmo3HAyxDma4SVWpbNqSjlpIgvSI947DUufpN/Vc= ARC-Message-Signature:i=3; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790845314; c=relaxed/simple; bh=l1Aa5ZkEkWLubJ7KAUKg1jiILLp4mk3J4ktz24EA8YI=; h=Message-ID:Date:Cc:Subject:To:References:From:In-Reply-To: Content-Type:MIME-Version; b=KJyIeI2o5b7OYqLsyFROlQGj/b4311EAbH6Vn4ywmUu4G9YK2CGiD/usmNNwVfkgvFQEGnnCX0t38MMb/XEHiw5ESvAr2lnPPy+WdnK2ynBjQY3npSthJOLJOJGu2y6FxsnNht+aNWNznL1p9fwjRLbS9xPX5zgVeVxuRwPGn8o= ARC-Authentication-Results:i=3; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=CuXwIjVo; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=CuXwIjVo; arc=fail smtp.client-ip=52.101.83.48 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="CuXwIjVo"; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="CuXwIjVo" ARC-Seal: i=2; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=pass; b=Qm9tmWdK6TImqwIDlH1CxEdRt+/UeHXg7/khrtnoa+f1aoUwb5jycO8D2CIAR6p1UflpAvUWgm+cU177oncP0TSi/HrNx5EQK4DDhnfqLrBDBD/Jagr49iInH27HtwFCDMIub9Kaeh3PW9GLxJi9N9jJ/TP1yglb+QAj++x1y2OLo3x9yR2Ps0qNsoy1SMCMpKHIC51x0F9sjboTMUMV/7bTE+n3G4SPtbF2ZGA6pQonR+NFwO9yJ75ulkYheoA3XSUNXggwgTMHtm3nTdtSliYd3Tsrd30DnbF+4AOETO3BreKoT/QelJAOZpG5HR27j85sbbskZUIEuRVvAxUgeA== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=8EMp9ioHsauhff6rt3MKJM8xAZeP5pGGXQEnrcrV4V0=; b=Y4S57JJ4XFRrBW+sWya2axn6FyDmHo99eS53l/PzJmbglSmKLGMVB5UKpec8xqWSAwb5BQsK8QUmQWZs3Z5QPXOmfwIzpIT7tBX1fL1noibxGTHdK7i1VG3pq56qe6TYztjrB8eGMcDAY4IzZimxPCvadFBFxfrfr+ljT5F1ulmQR9c7Td2/IW7KcuOu0YvjKdekynAmYfqAwdSbVgiSXx0p19nsyyjwZ3qJgl6MAhOnHtUckp099hBD/npJRlq1RQNACJw2jUJ+fGgAkuoadeC1Nn43rgrEFKr636UaMSfBueaTeDF+3HFj+3RXlYQHfq0LFwRV1DkL1X4vJlbn7g== ARC-Authentication-Results: i=2; mx.microsoft.com 1; spf=pass (sender ip is 4.158.2.129) smtp.rcpttodomain=kernel.org smtp.mailfrom=arm.com; dmarc=pass (p=none sp=none pct=100) action=none header.from=arm.com; dkim=pass (signature was verified) header.d=arm.com; arc=pass (0 oda=1 ltdi=1 spf=[1,1,smtp.mailfrom=arm.com] dkim=[1,1,header.d=arm.com] dmarc=[1,1,header.from=arm.com]) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arm.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=8EMp9ioHsauhff6rt3MKJM8xAZeP5pGGXQEnrcrV4V0=; b=CuXwIjVowtzJt/N4h4jDeeQ8PJpGR0x1ULYGUq3ZnBaXpOCDzTunp1PkK4yTC1Gc4Blxi5+QUgTjlBZwp8u++E3mailxTUl1dIy88G5gXz1Vw19ocY8UbMlH78nrs98cQ1ZVMYkAKq3Wq8YolRQqefWCM9Gz8brCUPktQLRRtOk= Received: from AM0P190CA0016.EURP190.PROD.OUTLOOK.COM (2603:10a6:208:190::26) by GV2PR08MB132880.eurprd08.prod.outlook.com (2603:10a6:150:3b9::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.472.15; Thu, 1 Oct 2026 09:01:48 +0000 Received: from AM2PEPF00070CF7.eurprd02.prod.outlook.com (2603:10a6:208:190:cafe::a9) by AM0P190CA0016.outlook.office365.com (2603:10a6:208:190::26) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.21.472.16 via Frontend Transport; Thu, 1 Oct 2026 09:01:46 +0000 X-MS-Exchange-Authentication-Results: mx.microsoft.com 1; spf=pass (sender IP is 4.158.2.129) smtp.mailfrom=arm.com; dkim=pass (signature was verified) header.d=arm.com;dmarc=pass action=none header.from=arm.com; Received-SPF: Pass (protection.outlook.com: domain of arm.com designates 4.158.2.129 as permitted sender) receiver=protection.outlook.com; client-ip=4.158.2.129; helo=outbound-uk1.az.dlp.m.darktrace.com; pr=C Received: from outbound-uk1.az.dlp.m.darktrace.com (4.158.2.129) by AM2PEPF00070CF7.mail.protection.outlook.com (10.167.242.9) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.21.472.14 via Frontend Transport; Thu, 1 Oct 2026 09:01:45 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=FuO4meA0nwIC2P2QP4E57xpg/UB5ZU3Ap7hOzhXHb4rs1kKslGda/Pnf9R2fYTBVdqt6l/fMOXa/EOOAfWxhFFQQKdyt1v9B6stjjJN31+nWWPMGhmNTqEjtAcwcczGtcqECsJMY2C11hV76efxPrbivUStFiERvWMLX8gOhjE4kktbN0LEJP3kg4paRDoGw3K0a3oaKn9aQClAnaCNn6w4Vr0NvBpZmHuZsMx6Cx4nzHXBkmq0GrLGbBZq3EYL6iNldQNuCqXZFAFY9IUAg3M3X7BXH8yWAnb711rDfoDGFyBRe6eInnl+X5zHUv2pyMbj7BAfzL2yrBHgldT3LxQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=8EMp9ioHsauhff6rt3MKJM8xAZeP5pGGXQEnrcrV4V0=; b=BBOIfl7bkMVt6SGJVgOuzmiyjgOLAwVCuI00yAA22fFNBALywdjyOQbpU/v+nzoH3PqCDqRNhNqDsoPnBoInDPym/V44m/t9BHWgCtk89eL4TQl84dtG1O55EvQjANosj93pe8xIdGO8UY66gPLRDOqgSiw8hahliAZnWg6XtunrjdHUcvYLpPecBs0+CdIq/Xo5s4o65B4pBiuS8Q6ZCKHlWIFNNFqdxCelMIot8jwMjRVO/sbWezT57/qbFsoSDxJQx1L5weT78ihOP85w2AUYPUfaz9Q72HTWnN2cy0VySnMDPi5ngXXOeaXwJCKF12VR2JTVd6SA8bWhYkjZyg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=arm.com; dmarc=pass action=none header.from=arm.com; dkim=pass header.d=arm.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arm.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=8EMp9ioHsauhff6rt3MKJM8xAZeP5pGGXQEnrcrV4V0=; b=CuXwIjVowtzJt/N4h4jDeeQ8PJpGR0x1ULYGUq3ZnBaXpOCDzTunp1PkK4yTC1Gc4Blxi5+QUgTjlBZwp8u++E3mailxTUl1dIy88G5gXz1Vw19ocY8UbMlH78nrs98cQ1ZVMYkAKq3Wq8YolRQqefWCM9Gz8brCUPktQLRRtOk= Authentication-Results-Original: mx.microsoft.com 1; dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=arm.com; Received: from VI1PR08MB3421.eurprd08.prod.outlook.com (2603:10a6:803:80::16) by VI1PR08MB10050.eurprd08.prod.outlook.com (2603:10a6:800:1c4::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.472.15; Thu, 1 Oct 2026 09:01:05 +0000 Received: from VI1PR08MB3421.eurprd08.prod.outlook.com ([fe80::e079:6bd:fbe0:89b4]) by VI1PR08MB3421.eurprd08.prod.outlook.com ([fe80::e079:6bd:fbe0:89b4%3]) with mapi id 15.21.0472.012; Thu, 1 Oct 2026 09:00:39 +0000 Message-ID: <15549877-85ad-49ad-b2f2-843dd506ba0a@arm.com> Date: Thu, 1 Oct 2026 10:00:37 +0100 User-Agent: Mozilla Thunderbird Cc: usama.anjum@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Arnd Bergmann , Ard Biesheuvel , Ada Couprie Diaz , David Hildenbrand , Catalin Marinas , Vladimir Murzin , Mark Rutland , Mostafa Saleh , Lorenzo Stoakes , Oliver Upton , Marc Zyngier Subject: Re: [PATCH v2 00/21] arm64: Move overflow sp into SP_EL1 and kernel sp into SP_EL0 To: Will Deacon , Linus Walleij References: <20260918161407.2300-1-will@kernel.org> From: Muhammad Usama Anjum Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: PR1P264CA0166.FRAP264.PROD.OUTLOOK.COM (2603:10a6:102:347::12) To VI1PR08MB3421.eurprd08.prod.outlook.com (2603:10a6:803:80::16) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-TrafficTypeDiagnostic: VI1PR08MB3421:EE_|VI1PR08MB10050:EE_|AM2PEPF00070CF7:EE_|GV2PR08MB132880:EE_ X-MS-Office365-Filtering-Correlation-Id: 45b9a402-c4b5-4940-00c8-08df1f9a9eb2 x-checkrecipientrouted: true NoDisclaimer: true X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam-Untrusted: BCL:0;ARA:13230040|23010399003|1800799024|366016|7416014|376014|10067099003|4143699003|56012099006|6133799003|11063799006|22082099003|18002099003; X-Microsoft-Antispam-Message-Info-Original: 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 X-Forefront-Antispam-Report-Untrusted: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:VI1PR08MB3421.eurprd08.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(23010399003)(1800799024)(366016)(7416014)(376014)(10067099003)(4143699003)(56012099006)(6133799003)(11063799006)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-Exchange-RoutingPolicyChecked: sMH8HdWcVWeCa/WxpdoVgCN1VEXyuiEz0Bj4tnvYzxw6F5VKyHtnitHi6fRP5ihPl7nqoRzKuJTe6B9kEKXTDF8zZ6+8qB/0SERPgVVFqjPUsqlfDG8AXZcCPhYa6jMwmye0FpEVlHqENu/4LlalGYlowhPd1ModnUKtRyZnREJ87dSlD2sNqv/u78athzqZTjVkN6Dse9V6hBN5829n0rnJsT3UHEja4KHKyh4wf92t1Xtgjy1wJsK9w5EdgVNX/pj6+D25Q+l2nW2VnyHaVOToGW9x5ZKP73oX9TRx4dEPDwNnECgj8Gjh5RpXrk9vPvg2/y/8dLvQQ9kRkJcUnA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR08MB10050 X-EOPAttributedMessage: 0 X-MS-Exchange-Transport-CrossTenantHeadersStripped: AM2PEPF00070CF7.eurprd02.prod.outlook.com X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id-Prvs: 18ed55b5-f719-4538-a868-08df1f9a7717 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|23010399003|14060799003|82310400026|35042699022|36860700016|4143699003|6133799003|10067099003|56012099006|11063799006|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:4.158.2.129;CTRY:GB;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:outbound-uk1.az.dlp.m.darktrace.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(376014)(23010399003)(14060799003)(82310400026)(35042699022)(36860700016)(4143699003)(6133799003)(10067099003)(56012099006)(11063799006)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: bDp//M8Opk5/oLFDT8QCKHBgB1ibxtonMQg53S/iPrhyO0WcmPb7KijARCkerDkX2tqQQXZY39yOQKwq6Ye7PlrMJnhp5b217OE7ufCwWPj0kXdq2HrUtF3XTcu1CCmdnaXPN9031td1P+FrqeekuLEKvcQ7v867H/2khWCxSrc7OnnEiejghSCCFOevLs71B9Tl8DwMrTDVRLia727kJLTMUci/JM+bI9LCC0/CJK65Voxoknkq+/Vm7pDlszmBiQt2VcWp9i8F0vJYsKeDnyxfbGsSfVKv023hPM4Na5NWKEgceUZRXh27f5zwhhT5SkpF0YE6vJ8/QUMDn7BWIbB408ru3OEPwqkJJRFY8zKusQTN3tujGX4LbLf+clh5VA80NJmNkzrZZL93zEWmzxRlKcFkdt8pwpU/UXABekXwzlvCf9bvSMhYzqUS2j6a X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Oct 2026 09:01:45.6884 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 45b9a402-c4b5-4940-00c8-08df1f9a9eb2 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[4.158.2.129];Helo=[outbound-uk1.az.dlp.m.darktrace.com] X-MS-Exchange-CrossTenant-AuthSource: AM2PEPF00070CF7.eurprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: GV2PR08MB132880 On 01/10/2026 8:21 am, Will Deacon wrote: > On Wed, Sep 30, 2026 at 11:42:51PM +0200, Linus Walleij wrote: >> On Fri, Sep 18, 2026 at 6:14 PM Will Deacon wrote: >> >>> This is version two of the kernel stack juggling patches I previously >>> posted here: >>> >>> https://lore.kernel.org/r/20260907164247.17223-1-will@kernel.org >>> >>> Changes since v1 include: >>> * Fixed suspend/resume paths to handle the stack pointers properly >>> * Fixed restoration of ptrauth keys on resume >>> * Added tags >> >> Overall I like what I see, but can we split it in two... like first the patches >> up to fixing the overflow handling using SP_EL0 and finalize that? > > Yes, that makes sense (and thanks for going through it). The whole thing > is bisectable, so lemme go through the feedback I've got so far and send > out a prefix that we could consider merging as preparatory work. I'll trigger run on this prefix. > >> Hopefully Usama can test just that part and see if it has a lesser >> performance impact as well. > > I'd like to see those numbers at various points during the series, tbh, > so we can rule out any stack-protector changes etc. Sure, I can trigger runs on different points if you can mention which would be more valuable. -- Thanks, Usama