From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 21984440874 for ; Thu, 13 Jul 2017 09:52:32 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id j85so4332838wmj.2 for ; Thu, 13 Jul 2017 06:52:32 -0700 (PDT) Received: from mail-wm0-x242.google.com (mail-wm0-x242.google.com. [2a00:1450:400c:c09::242]) by mx.google.com with ESMTPS id k205si5373624wmf.17.2017.07.13.06.52.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Jul 2017 06:52:30 -0700 (PDT) Received: by mail-wm0-x242.google.com with SMTP id y5so5254451wmh.3 for ; Thu, 13 Jul 2017 06:52:30 -0700 (PDT) Date: Thu, 13 Jul 2017 16:52:28 +0300 From: "Kirill A. Shutemov" Subject: Re: KASAN vs. boot-time switching between 4- and 5-level paging Message-ID: <20170713135228.vhvpe7mqdcqzpslw@node.shutemov.name> References: <20170710212403.7ycczkhhki3vrgac@node.shutemov.name> <20170711103548.mkv5w7dd5gpdenne@node.shutemov.name> <20170711170332.wlaudicepkg35dmm@node.shutemov.name> <20170711190554.zxkpjeg2bt65wtir@black.fi.intel.com> <20939b37-efd8-2d32-0040-3682fff927c2@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20939b37-efd8-2d32-0040-3682fff927c2@virtuozzo.com> Sender: owner-linux-mm@kvack.org List-ID: 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 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. > --- > arch/x86/mm/dump_pagetables.c | 22 ++++++++++++++++------ > 1 file changed, 16 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c > index 0470826d2bdc..36515fba86b0 100644 > --- a/arch/x86/mm/dump_pagetables.c > +++ b/arch/x86/mm/dump_pagetables.c > @@ -13,6 +13,7 @@ > */ > > #include > +#include > #include > #include > #include can be dropped. And I don't think it compiles with KASAN disabled. For reference, the patch I use now: https://git.kernel.org/pub/scm/linux/kernel/git/kas/linux.git/commit/?h=la57/boot-switching/v2&id=c4b1439f719b1689a1cfca9c0df17b9f8b8462b9 -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org