From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 594062857CC; Fri, 17 Apr 2026 15:59:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776441577; cv=none; b=P8Nr+qFHzrJ7tI1eFBNR+KqiZ6HTMXmGhJhnj0bxzWYL73guCL2VxbtEKckkr/Gsqv53iBgnWbQzlQzA8FJy1VhwMbjG8+rARliuw/lFTmk+QgDgSFcFTeV2pBsMZ4t6DnSr8zOm4LSYUwgkw+Mt8KBc624lfxa4IpFr2OE66e4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776441577; c=relaxed/simple; bh=j8FO8PzF0PieyWhQwCeTDRN7VIBMniarhO6pmXOcNmE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RLHuypQ0WVH7M/yolfS8ymRfBJINH/fKdGQW59jMyBVot1MyF9zyTd1VI48bWuEG3cLHyhre0I3VunXFToDIuvEfqU9yz1WA0Y0mso2zpX0eIf3oHkNu8l+TuJp3fGk5xxg9rM535to0M07E1dlvOrc2Y0/6YITpVD0kcdR/CDA= ARC-Authentication-Results:i=1; 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=dKqzTM+j; arc=none smtp.client-ip=217.140.110.172 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="dKqzTM+j" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0B11D1DB5; Fri, 17 Apr 2026 08:59:30 -0700 (PDT) Received: from [10.57.63.31] (unknown [10.57.63.31]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 338A23F7D8; Fri, 17 Apr 2026 08:59:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1776441575; bh=j8FO8PzF0PieyWhQwCeTDRN7VIBMniarhO6pmXOcNmE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=dKqzTM+j4F58kIlpCMfJfslXRAvTIV63Jvs8XKtFPmTHYNKP2Hv8L1yPWqACikmRb b+TajA/SlxbTw4g2mMiYjf5eL8R/K3voQJzpqhOA7XvIo434idPxeQ4QAJe9tq+kr2 S45xgvtee1/IiZZgthWVd5FLYan71Tu1mwyJ2OjU= Message-ID: <913002a5-e002-4001-ad19-037102d1f97d@arm.com> Date: Fri, 17 Apr 2026 17:59:26 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 01/30] mm: Introduce kpkeys To: "David Hildenbrand (Arm)" , linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Andy Lutomirski , Catalin Marinas , Dave Hansen , Ira Weiny , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Lorenzo Stoakes , Marc Zyngier , Mark Brown , Matthew Wilcox , Maxwell Bland , "Mike Rapoport (IBM)" , Peter Zijlstra , Pierre Langlois , Quentin Perret , Rick Edgecombe , Ryan Roberts , Thomas Gleixner , Vlastimil Babka , Will Deacon , Yang Shi , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org References: <20260227175518.3728055-1-kevin.brodsky@arm.com> <20260227175518.3728055-2-kevin.brodsky@arm.com> <00b24db8-0063-48d6-8bc4-e8b670d8f0d5@kernel.org> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: <00b24db8-0063-48d6-8bc4-e8b670d8f0d5@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 17/04/2026 16:37, David Hildenbrand (Arm) wrote: > On 2/27/26 18:54, Kevin Brodsky wrote: >> kpkeys is a simple framework to enable the use of protection keys >> (pkeys) to harden the kernel itself. This patch introduces the basic >> API in : a couple of functions to set and restore >> the pkey register and macros to define guard objects. >> >> kpkeys introduces a new concept on top of pkeys: the kpkeys level. >> Each level is associated to a set of permissions for the pkeys >> managed by the kpkeys framework. kpkeys_set_level(lvl) sets those >> permissions according to lvl, and returns the original pkey >> register, to be later restored by kpkeys_restore_pkey_reg(). To >> start with, only KPKEYS_LVL_DEFAULT is available, which is meant >> to grant RW access to KPKEYS_PKEY_DEFAULT (i.e. all memory since >> this is the only available pkey for now). >> >> Because each architecture implementing pkeys uses a different >> representation for the pkey register, and may reserve certain pkeys >> for specific uses, support for kpkeys must be explicitly indicated >> by selecting ARCH_HAS_KPKEYS and defining the following functions in >> , in addition to the macros provided in >> : >> >> - arch_kpkeys_set_level() >> - arch_kpkeys_restore_pkey_reg() >> - arch_kpkeys_enabled() > Another thing: why not simply drop the "arch_" stuff from these helpers? The first two are not meant to be directly called, they're the arch-specific implementation of kpkeys_set_level() and kpkeys_restore_pkey_reg(), and those generic functions handle some generic logic. arch_kpkeys_enabled() is directly used in generic code, so I suppose it could be renamed to kpkeys_enabled()? It's actually implemented in an arch header so I wasn't too sure about it. - Kevin