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 3BEBAC43458 for ; Fri, 3 Jul 2026 05:30:56 +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=pmNFIi7RnnrypKskw6fwxOk6ivWwb+ik3iVKHlwrVrI=; b=yhJ7IuwMAoa9oiIsE3qkMVjVx0 OUgb1J7sn8Tkn6eadT87/MMZjLwlYNu9XRYRtaABjVQlPQpmby11Xr6BB/QM1cys1rxZNskB4M5rS ha12oGTCya8VXcZVURzAUNMxdtrw/HuzGspJ9q9x2Y1XO9reWdQa69da9aCdIcW3rft27le19VXXY v+prxj4SoiOMR8qxLwiH+rQyAAeN3cp9bMTkWAYAXlhE6TkTp5HwCGcO/+ZzlzfQ04TePDVqo4guL 1gQjel0g/BQCXQ8lxmh/kpxwiavtqgIhZAwIVnzV5QFL/HV9RjsYDlSKgx2zysPoaYqQEoXnwBfUY I9LEiCYw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wfWUC-000000064G9-3Ed0; Fri, 03 Jul 2026 05:30:48 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wfWUA-000000064FU-1Nfj for linux-arm-kernel@lists.infradead.org; Fri, 03 Jul 2026 05:30:47 +0000 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 19BAB1D34; Thu, 2 Jul 2026 22:30:40 -0700 (PDT) Received: from [10.164.19.15] (unknown [10.164.19.15]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 93E953F673; Thu, 2 Jul 2026 22:30:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783056644; bh=x/FZbZRvlfgDKJ87XGqUbVjYmJN5YLYtikgDpbbk+3s=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=gRZT5Aycj8nb9nzE9CkfCAmO1Pk+zt96vwJ0a+6cKk6Wn/mIV1tYxcrUG/53HkHzj hn2MLdJulVDpzweQyjtnhqxSXAs3RDgKOuCTNjnCpg+4zOinXDuxDvU/Xyloz5ww/k V36SggskoTyyC6c++z8jGDd4uZBRW8buLuFGqQZY= Message-ID: <1ef238fd-232c-4b8a-b28d-cd20db57bcfc@arm.com> Date: Fri, 3 Jul 2026 11:00:32 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 6/6] mm/mprotect: use huge_ptep_get() for hugetlb To: "David Hildenbrand (Arm)" , 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> Content-Language: en-US From: Dev Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260702_223046_420746_DAD386FB X-CRM114-Status: GOOD ( 17.69 ) 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 02/07/26 9:17 pm, David Hildenbrand (Arm) wrote: > 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; > Sure I'll do this. >