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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5A72C4BA24 for ; Thu, 27 Feb 2020 04:04:10 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 97A9824685 for ; Thu, 27 Feb 2020 04:04:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Tzu2nBA2"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="hEshnkY+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 97A9824685 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: Content-Transfer-Encoding:Content-Type:Mime-Version:References:In-Reply-To: Message-Id:Subject: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=N46TkGmJeEVwSldQB0zOVw2kGLcNhjqd1CBeetTF/NM=; b=Tzu2nBA2EFea/N IzL4YQjcN4bpEWCJmdppoaXV3oxEek0x40iHDt0VhJ2CZm2qUWmSfGRGh2M4AiReUJUYPajFrL+1d tIr/aM0C3/m3+U47BgPmTkpm602V6W5D/6DQLfud55T81CAbrXqQTfs0DPs5hayPa4z2HYNuiDBrJ 6ZcBVgAZEnivmS/Cl0Wo4D78sObWlQiPpRVwrFa6KUCd670mHnOtoRSssdKdf/iDe2LoaVibzwzNY l5gn/fxTpsWHHwHNgQNce5pBxdpdsnEcEZEIMV6xCpISHSE5lAarXtY7YnjX8rMw5st36YVOfuk7Y sNqF/l8fx1w09i676HxQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j7AP8-0001Wd-Kz; Thu, 27 Feb 2020 04:04:06 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j7AOx-0001NZ-MG; Thu, 27 Feb 2020 04:03:57 +0000 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D80E124685; Thu, 27 Feb 2020 04:03:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582776234; bh=dlJV6X0I7IrGWbU/KtcbtANr08nwFCVTfE1alETj44U=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=hEshnkY+tvGit0cKDfeluAySLkQ4Xled8zmc5jvOITOHKbmYgwRCgZhr11yYlZCaI QkeZdgAbSbrNzA3JROFuXOzJ0V7vmn3oqMn/+vctVVCl4wtBE8lv4P5PYNPqJ5zhBr 6sL43sJMfYsduFtDrJ6WJ+ZOQLAYvoMayLwJqBKk= Date: Wed, 26 Feb 2020 20:03:53 -0800 From: Andrew Morton To: Anshuman Khandual Subject: Re: [PATCH V14] mm/debug: Add tests validating architecture page table helpers Message-Id: <20200226200353.ea5c8ec2efacfb1192f3f3f4@linux-foundation.org> In-Reply-To: <52db1e9b-83b3-c41f-ef03-0f43e2159a83@arm.com> References: <1581909460-19148-1-git-send-email-anshuman.khandual@arm.com> <1582726182.7365.123.camel@lca.pw> <1582726340.7365.124.camel@lca.pw> <52db1e9b-83b3-c41f-ef03-0f43e2159a83@arm.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200226_200355_774378_1AED5004 X-CRM114-Status: GOOD ( 18.14 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Benjamin Herrenschmidt , Heiko Carstens , linux-mm@kvack.org, Paul Mackerras , "H. Peter Anvin" , linux-riscv@lists.infradead.org, Will Deacon , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Michael Ellerman , x86@kernel.org, Mike Rapoport , Christian Borntraeger , Ingo Molnar , Catalin Marinas , James Morse , linux-snps-arc@lists.infradead.org, Vasily Gorbik , Qian Cai , Paul Walmsley , "Kirill A . Shutemov" , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Christophe Leroy , Vineet Gupta , linux-kernel@vger.kernel.org, Palmer Dabbelt , Borislav Petkov , linuxppc-dev@lists.ozlabs.org Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On Thu, 27 Feb 2020 08:04:05 +0530 Anshuman Khandual wrote: > > Must be something wrong with the following in debug_vm_pgtable() > >=20 > > =A0=A0=A0=A0paddr =3D __pa(&start_kernel); > >=20 > > Is there any explaination why start_kernel() is not in linear memory on= ARM64 ? >=20 >=20 > Cc: + James Morse >=20 > This warning gets exposed with DEBUG_VIRTUAL due to __pa() on a kernel sy= mbol > i.e 'start_kernel' which might be outside the linear map. This happens du= e to > kernel mapping position randomization with KASLR. Adding James here in ca= se he > might like to add more. >=20 > __pa_symbol() should have been used instead, for accessing the physical a= ddress > here. On arm64 __pa() does check for linear address with __is_lm_address(= ) and > switch accordingly if it is a kernel text symbol. Nevertheless, its much = better > to use __pa_symbol() here rather than __pa(). >=20 > Rather than respining the patch once more, will just send a fix replacing= this > helper __pa() with __pa_symbol() for Andrew to pick up as this patch is a= lready > part of linux-next (next-20200226). But can definitely respin if that wil= l be > preferred. I didn't see this fix? I assume it's this? If so, are we sure it's OK to = be added to -next without testing?? From: Andrew Morton Subject: mm-debug-add-tests-validating-architecture-page-table-helpers-fix A warning gets exposed with DEBUG_VIRTUAL due to __pa() on a kernel symbol i.e 'start_kernel' which might be outside the linear map. This happens due to kernel mapping position randomization with KASLR. __pa_symbol() should have been used instead, for accessing the physical address here. On arm64 __pa() does check for linear address with __is_lm_address() and switch accordingly if it is a kernel text symbol.=20 Nevertheless, its much better to use __pa_symbol() here rather than __pa(). Reported-by: Qian Cai Cc: Anshuman Khandual Cc: James Morse Cc: Christophe Leroy Signed-off-by: Andrew Morton --- mm/debug_vm_pgtable.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/debug_vm_pgtable.c~mm-debug-add-tests-validating-architecture-page= -table-helpers-fix +++ a/mm/debug_vm_pgtable.c @@ -331,7 +331,7 @@ void __init debug_vm_pgtable(void) * helps avoid large memory block allocations to be used for mapping * at higher page table levels. */ - paddr =3D __pa(&start_kernel); + paddr =3D __pa_symbol(&start_kernel); =20 pte_aligned =3D (paddr & PAGE_MASK) >> PAGE_SHIFT; pmd_aligned =3D (paddr & PMD_MASK) >> PAGE_SHIFT; _