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 75A9BC5DF81 for ; Wed, 19 Aug 2026 07:14:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=4XqBLFLSS8PKktDleqDE1jOZr/vcplyhd4oOF1nI+k8=; b=Uz0rWUsUgzUJE9 tF6M0X93lsNPFVUMz1CrLzFD4HOcz0sExRfZ6hP5lkoBfxVAZk1TPogKl26FY2w2vW6g5dpDGBD+N zX5Xj3A5Y3ozwzn4667vJS21JlE8nm1467sHbbO7l3SGB8LEJlltNrM9Nyolc1N73XoTF2pN+6XVu f3Ag7J3GkND3WiV8LtXcJQmgDcBMkMvHxzV9n/Kgg6FykOUPsLpQQkHSgDGsUvWTtV1d/cBkp98FS vAgyIgYm6XsoBl+nuDXPV0RTSL+xiIt+/MNMEx14jaRTnsMhn3htj+85Md7TKFlhK4rHvktcpnxva GtlODpKcOchM4V6xEnDQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wwaUn-00000009AVL-0945; Wed, 19 Aug 2026 07:13:57 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wwaUl-00000009AUo-2hAA; Wed, 19 Aug 2026 07:13:55 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id B0871601FB; Wed, 19 Aug 2026 07:13:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FCAB1F000E9; Wed, 19 Aug 2026 07:13:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787123634; bh=MEh93umEkAdwM7W7h5DMLx7l0jri6Tex4Ey3QmOKRt0=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=jJV0OzwVbpNuL1O7IKYFMOfkJNn5jUunHF3YbR6s3DRCL2TlLVhLPBotWdiGtRokA tmvHyqyp+imK+t1Fq3nxpk977s16W+HIjEKyInWVUV1oA//lPAb6rPWocpZquA5Ccm bgwCf3DzoBtBiJCPGwlFz9HjCr/lq2MMwhpgdxHoSsupRhmU3NSJ07HL6c5BUc2jmQ uN/InEQopdQkSXzswZqrN8YxkDoenas2ccCQodY70U8cWRig2OBGou4vh1U4PakYtX vAKsses0e/ZiFmKxHArYa8yhDZVE4w8x5VBUX22681OzmQsFslwRWWGAKw1WggWAbV zsPrgq11T43eA== Date: Wed, 19 Aug 2026 10:13:38 +0300 From: Mike Rapoport To: Brendan Jackman Cc: Andrew Morton , Adrian =?utf-8?Q?Barna=C5=9B?= , Albert Ou , Alexander Gordeev , Alexandre Ghiti , Andy Lutomirski , Borislav Petkov , Catalin Marinas , Christian Borntraeger , Dave Hansen , David Hildenbrand , Gerald Schaefer , Heiko Carstens , Huacai Chen , Ingo Molnar , Len Brown , Palmer Dabbelt , Paul Walmsley , Pavel Machek , Peter Zijlstra , "H. Peter Anvin" , "Rafael J. Wysocki" , Ryan Roberts , Sven Schnelle , Thomas Gleixner , Uladzislau Rezki , Vasily Gorbik , WANG Xuerui , Will Deacon , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pm@vger.kernel.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, loongarch@lists.linux.dev, yosry@kernel.org Subject: Re: [PATCH 6/6] Revert "arch: introduce set_direct_map_valid_noflush()" Message-ID: References: <20260816-execmem-set-vm-perms-v0-2-v1-0-90944a3ad43f@kernel.org> <20260816-execmem-set-vm-perms-v0-2-v1-6-90944a3ad43f@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Mon, Aug 17, 2026 at 05:14:19PM +0200, Brendan Jackman wrote: > On Sun Aug 16, 2026 at 12:59 PM CEST, Mike Rapoport (Microsoft) wrote: > > Commit 0c6378a71574 ("arch: introduce set_direct_map_valid_noflush()") > > added set_direct_map_valid_noflush() to allow updating the direct map > > for a physically contiguous range in execmem. > > > > As Brendan recently pointed out [1], this API is confusing because on > > arm64 it means that is sets VALID bit in ptes, while on other > > architectures it is an analog of set_direct_map_default_noflush(). > > > > The only user of set_direct_map_valid_noflush() was execmem's ROX cache > > freeing path and it was switched to utilize VM_FLUSH_RESET_PERMS for > > resetting permissions of the direct map alias. > > > > With the last user gone and with set_direct_map_{invalid,default}_noflush() > > accepting number of pages as a parameter, set_direct_map_valid_noflush() > > become a copy of set_memory_valid() on arm64 and a duplicate of > > set_direct_map_{invalid,default}_noflush() on other architecture, it is > > safe to remove set_direct_map_valid_noflush(). > > > > Also drop a stale comment in arm64::__kernel_map_pages() that Linus > > bothered to add when merging changes containing set_direct_map_valid_noflush() > > to his tree. > > > > This reverts commit 0c6378a71574daa6cd1534ad42a956e3262756c7. > > > > [1] https://lore.kernel.org/all/DJ69RCVRBO0Y.3JCYSW50IC4RC@linux.dev > > > > Signed-off-by: Mike Rapoport (Microsoft) > > So basically the big issue here is specifically that > set_direct_map_valid_noflush(..., true) is special on arm64 and not x86. More precisely arm64 differers from all the rest. > And we fix that by jut deleting the API. SGTM! > > The other issue I can see here is that set_direct_map_invalid_noflush() > clears RW on x86 but doesn't set RDONLY on arm64. So if you unmap > something using set_direct_map_invalid_noflush(), then map it again > using something other than set_direct_map_default_noflush(), you get > different behaviour between the archs. > > I think the answer to that is probably: doing that is a bug, i.e. > _invalid_noflush() and _default_noflush() are a pair that you have to > use together. But I haven't checked if this is currently the case. Maybe > it would still make sense to just align these fully? All set_memory + set_direct_map functions very much rely on caller to know how to use them right. There were only handful of users outside of arch/ so it was kinda sustainable. With the increased demand for those, security and whatnot, the whole bunch of set_memory functions needs some love. > Anyway, aside from all this yapping, getting rid of _valid_noflush() > seems like an unambiguous win here so thanks for the cleanup! > > Reviewed-by: Brendan Jackman -- Sincerely yours, Mike. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv