Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752700AbdGMOPf (ORCPT ); Thu, 13 Jul 2017 10:15:35 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:32988 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752314AbdGMOPb (ORCPT ); Thu, 13 Jul 2017 10:15:31 -0400 Date: Thu, 13 Jul 2017 17:15:28 +0300 From: "Kirill A. Shutemov" To: Andrey Ryabinin Cc: "Kirill A. Shutemov" , Andy Lutomirski , Dmitry Vyukov , Alexander Potapenko , Linus Torvalds , Andrew Morton , "x86@kernel.org" , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andi Kleen , Dave Hansen , linux-arch , "linux-mm@kvack.org" , LKML , kasan-dev Subject: Re: KASAN vs. boot-time switching between 4- and 5-level paging Message-ID: <20170713141528.rwuz5n2p57omq6wi@node.shutemov.name> References: <20170711103548.mkv5w7dd5gpdenne@node.shutemov.name> <20170711170332.wlaudicepkg35dmm@node.shutemov.name> <20170711190554.zxkpjeg2bt65wtir@black.fi.intel.com> <20939b37-efd8-2d32-0040-3682fff927c2@virtuozzo.com> <20170713135228.vhvpe7mqdcqzpslw@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170713135228.vhvpe7mqdcqzpslw@node.shutemov.name> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4213 Lines: 80 On Thu, Jul 13, 2017 at 04:52:28PM +0300, Kirill A. Shutemov wrote: > On Thu, Jul 13, 2017 at 03:58:29PM +0300, Andrey Ryabinin wrote: > > On 07/11/2017 10:05 PM, Kirill A. Shutemov wrote: > > >>> Can use your Signed-off-by for a [cleaned up version of your] patch? > > >> > > >> Sure. > > > > > > Another KASAN-releated issue: dumping page tables for KASAN shadow memory > > > region takes unreasonable time due to kasan_zero_p?? mapped there. > > > > > > The patch below helps. Any objections? > > > > > > > Well, page tables dump doesn't work at all on 5-level paging. > > E.g. I've got this nonsense: > > > > .... > > ---[ Kernel Space ]--- > > 0xffff800000000000-0xffff808000000000 512G pud > > ---[ Low Kernel Mapping ]--- > > 0xffff808000000000-0xffff810000000000 512G pud > > ---[ vmalloc() Area ]--- > > 0xffff810000000000-0xffff818000000000 512G pud > > ---[ Vmemmap ]--- > > 0xffff818000000000-0xffffff0000000000 128512G pud > > ---[ ESPfix Area ]--- > > 0xffffff0000000000-0x0000000000000000 1T pud > > 0x0000000000000000-0x0000000000000000 0E pgd > > 0x0000000000000000-0x0000000000001000 4K RW PCD GLB NX pte > > 0x0000000000001000-0x0000000000002000 4K pte > > 0x0000000000002000-0x0000000000003000 4K ro GLB NX pte > > 0x0000000000003000-0x0000000000004000 4K pte > > 0x0000000000004000-0x0000000000007000 12K RW GLB NX pte > > 0x0000000000007000-0x0000000000008000 4K pte > > 0x0000000000008000-0x0000000000108000 1M RW GLB NX pte > > 0x0000000000108000-0x0000000000109000 4K pte > > 0x0000000000109000-0x0000000000189000 512K RW GLB NX pte > > 0x0000000000189000-0x000000000018a000 4K pte > > 0x000000000018a000-0x000000000018e000 16K RW GLB NX pte > > 0x000000000018e000-0x000000000018f000 4K pte > > 0x000000000018f000-0x0000000000193000 16K RW GLB NX pte > > 0x0000000000193000-0x0000000000194000 4K pte > > ... 304 entries skipped ... > > ---[ EFI Runtime Services ]--- > > 0xffffffef00000000-0xffffffff80000000 66G pud > > ---[ High Kernel Mapping ]--- > > 0xffffffff80000000-0xffffffffc0000000 1G pud > > ... > > Hm. I don't see this: > > ... > [ 0.247532] 0xff9e938000000000-0xff9f000000000000 111104G p4d > [ 0.247733] 0xff9f000000000000-0xffff000000000000 24P pgd > [ 0.248066] 0xffff000000000000-0xffffff0000000000 255T p4d > [ 0.248290] ---[ ESPfix Area ]--- > [ 0.248393] 0xffffff0000000000-0xffffff8000000000 512G p4d > [ 0.248663] 0xffffff8000000000-0xffffffef00000000 444G pud > [ 0.248892] ---[ EFI Runtime Services ]--- > [ 0.248996] 0xffffffef00000000-0xfffffffec0000000 63G pud > [ 0.249308] 0xfffffffec0000000-0xfffffffefe400000 996M pmd > ... > > Do you have commit "x86/dump_pagetables: Generalize address normalization" > in your tree? > > https://git.kernel.org/pub/scm/linux/kernel/git/kas/linux.git/commit/?h=la57/boot-switching/v2&id=13327fec85ffe95d9c8a3f57ba174bf5d5c1fb01 > > > As for KASAN, I think it would be better just to make it work faster, > > the patch below demonstrates the idea. > > Okay, let me test this. The patch works for me. The problem is not exclusive to 5-level paging, so could you prepare and push proper patch upstream? -- Kirill A. Shutemov