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 E906EC43602 for ; Thu, 2 Jul 2026 15:47:38 +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:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=7HcBwq2b8wbb+HlpbEMWa8xWUd7UzW+LJArnIvi3VBc=; b=Fwb1b4Mf+Vt1iINKww+Jv5KWs7 W+clYBa4brmX5k2sePbaalXrw+av95d9gUnsC55jeA2c+F/5Yxmka3EOXu3TgoqHxqWeil720omOA GYCx0yI1WiH4nCdHCK6yjfQffpG07Tejr4zYL3MIF/JWeNG7YFBiKWrWNdVLKWxo7Lt+6LralDn+t A7hfJJOVFw4C1i9LSH5NyKRK0SA/H0XMY+luVFW7PoBWPKAYWfxZ3nyMu8u4Wv5uDrwEherZlNi6a iPK8CMri3/5Gb+lQrvc1eQDvYd9nWrBuurD7UPQ7c+LmSdst0muOT/O03s83DvvJX3jf7TY1PgDwN OyAGmqqw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wfJdU-00000004rBw-2BCn; Thu, 02 Jul 2026 15:47:32 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wfJdT-00000004rBh-3uY3 for linux-arm-kernel@lists.infradead.org; Thu, 02 Jul 2026 15:47:31 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 97B4940DE0; Thu, 2 Jul 2026 15:47:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF1341F000E9; Thu, 2 Jul 2026 15:47:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783007251; bh=7HcBwq2b8wbb+HlpbEMWa8xWUd7UzW+LJArnIvi3VBc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=JG+gPzUHCApSyS7KTNybCh1RpLBktz6oIyaZDWmOi0SQTnhEjoEI6jCdpVpLGBcYJ YlzbQgJK8V9CUmLTiCUoKNVE/vnqM4spBQrykU7mgr5rgO6FgT6zixT+YFzhKYd2nz 4HgP7gFqa4WQQ3EuAbsbFr7vbbiAE0NkXRYU7mOhrK0vljIyofpvoBDSAbjka24F/v +qCIj+3bl4hbrsXbjzgl3RXAMnPR+nglLhWpRPApW4zmOTRweXuUn32TnAuoNatI5+ TKt06gOrLyoGLh246TWxskSpPmyRboN3kf2+iVja9ngB8CpBKzTuKocPOoPzhwn8bZ YGh572WwZ8u6A== Message-ID: Date: Thu, 2 Jul 2026 17:47:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 6/6] mm/mprotect: use huge_ptep_get() for hugetlb To: Dev Jain , muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org Cc: riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, kas@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcampbell@nvidia.com, apopple@nvidia.com, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, j-nomura@ce.jp.nec.com, nao.horiguchi@gmail.com, ak@linux.intel.com, mel@csn.ul.ie, pfalcato@suse.de, jpoimboe@kernel.org, dave.hansen@intel.com, tglx@kernel.org, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260702051341.126509-1-dev.jain@arm.com> <20260702051341.126509-7-dev.jain@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: linux-arm-kernel@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-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 7/2/26 07:13, Dev Jain wrote: > prot_none_hugetlb_entry() is the hugetlb callback for the early > mprotect(PROT_NONE) PFN permission walk on x86. > > The callback passes the decoded PFN to pfn_modify_allowed(). For a > hugetlb callback, the pte pointer refers to a hugetlb entry. On > architectures where hugetlb entries need huge_ptep_get(), reading that > entry with ptep_get() can make the permission check use the wrong PFN. > > Use huge_ptep_get() before decoding the hugetlb PFN. > > Currently there is no path which can trigger a bug: huge_ptep_get() is a > simple ptep_get() for x86, and the prot_none walk occurs only for x86. > > So no need to backport - use the correct helper anyways. > > Fixes: 42e4089c7890 ("x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings") > Signed-off-by: Dev Jain > --- > mm/mprotect.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/mm/mprotect.c b/mm/mprotect.c > index 9cbf932b028cf..23779632d18bf 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -699,14 +699,20 @@ static int prot_none_pte_entry(pte_t *pte, unsigned long addr, > 0 : -EACCES; > } > > +#ifdef CONFIG_HUGETLB_PAGE > static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, > unsigned long addr, unsigned long next, > struct mm_walk *walk) > { > - return pfn_modify_allowed(pte_pfn(ptep_get(pte)), > + pte_t entry = huge_ptep_get(walk->mm, addr, pte); Nit: can be const :) > + > + return pfn_modify_allowed(pte_pfn(entry), > *(pgprot_t *)(walk->private)) ? > 0 : -EACCES; Indentation is odd. Can we just make this readable? if (pfn_modify_allowed ...) return 0 return -EACCESS; -- Cheers, David