From nobody Wed Dec 24 16:17:18 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 740C2135A45 for ; Thu, 25 Jan 2024 19:32:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706211169; cv=none; b=CPYgHcYeDLPiV+98dgZC1SXy8FnnAu1r/93s7kJylZY73y8LLr80Yojlclv1fPvNwycDwSgp9EwX1ZBcnPIRy9TBT6pgsqhgaYMvYU+ZvKurVYOa1pAMM0vuqm0AYp3fjAMEDbVZsynR7SQzgx1bLGmd6pWNuNcmtXY1Yaktw4I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706211169; c=relaxed/simple; bh=JYQIvwrSbs4WLbdMd4PO+glWKzAtVLKz+1fWwPw0FNE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=S1pDm6TOhTGJFjtdT7s6t/yd0heyySFFJy+Rfj+9PycDIanEB3mHDHpoH8bXRGDuJrhoGuOwS7C5S3/UH6Ko5oVw+phy//1XSd0Bvj01xr6oNXsLXVpcDq9jb/v2v7CBS4h5LdXFDSHamlH5/zWOYUmmjk1hTrXKds7dL24+XRk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=S62N9o3p; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="S62N9o3p" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1706211166; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=82AmjG/O5udPRimJWVv8/kqN5WdZj3aSPBj/SjaK3u4=; b=S62N9o3pikqaOBOr/Na222g/JLhRYzYPiVMP+GcGw6L5Cw+hxQKUNYHyADo1J0B1+Q2tuQ fknCq8WPzEc2dr1SixRCqay7iR2SzNlYPgm8Ryqy8AmWCRvCXCN2U80kjouxo7N3jC1vpX si9JTBm/ktie7CrlHIBsvGtCGZfVBEM= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-581-J0yUPAt0OCGNPncPGz6sEA-1; Thu, 25 Jan 2024 14:32:42 -0500 X-MC-Unique: J0yUPAt0OCGNPncPGz6sEA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EFA1F8432A6; Thu, 25 Jan 2024 19:32:40 +0000 (UTC) Received: from t14s.redhat.com (unknown [10.39.193.154]) by smtp.corp.redhat.com (Postfix) with ESMTP id 81D45492BC6; Thu, 25 Jan 2024 19:32:35 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, David Hildenbrand , Andrew Morton , Matthew Wilcox , Ryan Roberts , Russell King , Catalin Marinas , Will Deacon , Dinh Nguyen , Michael Ellerman , Nicholas Piggin , Christophe Leroy , "Aneesh Kumar K.V" , "Naveen N. Rao" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , "David S. Miller" , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org Subject: [PATCH v2 01/15] arm64/mm: Make set_ptes() robust when OAs cross 48-bit boundary Date: Thu, 25 Jan 2024 20:32:13 +0100 Message-ID: <20240125193227.444072-2-david@redhat.com> In-Reply-To: <20240125193227.444072-1-david@redhat.com> References: <20240125193227.444072-1-david@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 Content-Type: text/plain; charset="utf-8" From: Ryan Roberts Since the high bits [51:48] of an OA are not stored contiguously in the PTE, there is a theoretical bug in set_ptes(), which just adds PAGE_SIZE to the pte to get the pte with the next pfn. This works until the pfn crosses the 48-bit boundary, at which point we overflow into the upper attributes. Of course one could argue (and Matthew Wilcox has :) that we will never see a folio cross this boundary because we only allow naturally aligned power-of-2 allocation, so this would require a half-petabyte folio. So its only a theoretical bug. But its better that the code is robust regardless. I've implemented pte_next_pfn() as part of the fix, which is an opt-in core-mm interface. So that is now available to the core-mm, which will be needed shortly to support forthcoming fork()-batching optimizations. Link: https://lkml.kernel.org/r/20240125173534.1659317-1-ryan.roberts@arm.c= om Fixes: 4a169d61c2ed ("arm64: implement the new page table range API") Closes: https://lore.kernel.org/linux-mm/fdaeb9a5-d890-499a-92c8-d171df43ad= 01@arm.com/ Signed-off-by: Ryan Roberts Reviewed-by: Catalin Marinas Reviewed-by: David Hildenbrand Signed-off-by: David Hildenbrand --- arch/arm64/include/asm/pgtable.h | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgta= ble.h index 79ce70fbb751c..52d0b0a763f16 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -341,6 +341,22 @@ static inline void __sync_cache_and_tags(pte_t pte, un= signed int nr_pages) mte_sync_tags(pte, nr_pages); } =20 +/* + * Select all bits except the pfn + */ +static inline pgprot_t pte_pgprot(pte_t pte) +{ + unsigned long pfn =3D pte_pfn(pte); + + return __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^ pte_val(pte)); +} + +#define pte_next_pfn pte_next_pfn +static inline pte_t pte_next_pfn(pte_t pte) +{ + return pfn_pte(pte_pfn(pte) + 1, pte_pgprot(pte)); +} + static inline void set_ptes(struct mm_struct *mm, unsigned long __always_unused addr, pte_t *ptep, pte_t pte, unsigned int nr) @@ -354,7 +370,7 @@ static inline void set_ptes(struct mm_struct *mm, if (--nr =3D=3D 0) break; ptep++; - pte_val(pte) +=3D PAGE_SIZE; + pte =3D pte_next_pfn(pte); } } #define set_ptes set_ptes @@ -433,16 +449,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte) return clear_pte_bit(pte, __pgprot(PTE_SWP_EXCLUSIVE)); } =20 -/* - * Select all bits except the pfn - */ -static inline pgprot_t pte_pgprot(pte_t pte) -{ - unsigned long pfn =3D pte_pfn(pte); - - return __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^ pte_val(pte)); -} - #ifdef CONFIG_NUMA_BALANCING /* * See the comment in include/linux/pgtable.h --=20 2.43.0