From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755126AbcETHP1 (ORCPT ); Fri, 20 May 2016 03:15:27 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:34144 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754331AbcETHPY (ORCPT ); Fri, 20 May 2016 03:15:24 -0400 Date: Fri, 20 May 2016 09:15:17 +0200 From: Ingo Molnar To: Logan Gunthorpe Cc: Stephen Smalley , Kees Cook , Ingo Molnar , x86@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Lutomirski , Borislav Petkov , Denys Vlasenko , Brian Gerst Subject: Re: PROBLEM: Resume form hibernate broken by setting NX on gap Message-ID: <20160520071517.GB14191@gmail.com> References: <573DF82D.50006@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <573DF82D.50006@deltatee.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Logan Gunthorpe wrote: > Hi, > > I have been working on a bug that causes my laptop to freeze during > resume from hibernation. I did a bisect to find the offending commit: > > [ab76f7b4ab] x86/mm: Set NX on gap between __ex_table and rodata > > There is more information in the bugzilla report [1] that > I've been working on but I will summarize things below. > > I've experienced intermittent but reproducible freezes when resuming > from hibernation since about kernel version 3.19. The freeze was > significantly more reproducible when a few applications were loaded > before hibernation and would largely not happen if hibernated > immediately after booting to a desktop. I did some tracing work to find > that the kernel gets as far as the resume_image call in > swsusp_arch_resume and I could not find any response from the image > kernel when I hit the bug. I also did testing that seemed to rule out > this being caused by a problematic driver. > > I did a successful bisect between 3.18 and 3.19 which found a bug in > commit f5b2831d6 that was then later fixed by commit 55696b1f66 in 4.4. > Then, I did a second bisect with a ported version of the fix to the > first bug and found commit ab76f7b4ab in 4.3 to also break hibernation > with what appears to be the exact same symptoms. Reverting that commit > in recent kernels up to and including 4.6 fixes the issue and restores > reliable hibernation. However, it's not at all clear to me why that > commit would cause this issue or how to fix the issue without reverting. I've attached that commit below and also Cc:-ed a few more people who might have an idea about why this regressed. Worst-case we'll have to revert it. Thanks, Ingo =================> >>From ab76f7b4ab2397ffdd2f1eb07c55697d19991d10 Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Thu, 1 Oct 2015 09:04:22 -0400 Subject: [PATCH] x86/mm: Set NX on gap between __ex_table and rodata Unused space between the end of __ex_table and the start of rodata can be left W+x in the kernel page tables. Extend the setting of the NX bit to cover this gap by starting from text_end rather than rodata_start. Before: ---[ High Kernel Mapping ]--- 0xffffffff80000000-0xffffffff81000000 16M pmd 0xffffffff81000000-0xffffffff81600000 6M ro PSE GLB x pmd 0xffffffff81600000-0xffffffff81754000 1360K ro GLB x pte 0xffffffff81754000-0xffffffff81800000 688K RW GLB x pte 0xffffffff81800000-0xffffffff81a00000 2M ro PSE GLB NX pmd 0xffffffff81a00000-0xffffffff81b3b000 1260K ro GLB NX pte 0xffffffff81b3b000-0xffffffff82000000 4884K RW GLB NX pte 0xffffffff82000000-0xffffffff82200000 2M RW PSE GLB NX pmd 0xffffffff82200000-0xffffffffa0000000 478M pmd After: ---[ High Kernel Mapping ]--- 0xffffffff80000000-0xffffffff81000000 16M pmd 0xffffffff81000000-0xffffffff81600000 6M ro PSE GLB x pmd 0xffffffff81600000-0xffffffff81754000 1360K ro GLB x pte 0xffffffff81754000-0xffffffff81800000 688K RW GLB NX pte 0xffffffff81800000-0xffffffff81a00000 2M ro PSE GLB NX pmd 0xffffffff81a00000-0xffffffff81b3b000 1260K ro GLB NX pte 0xffffffff81b3b000-0xffffffff82000000 4884K RW GLB NX pte 0xffffffff82000000-0xffffffff82200000 2M RW PSE GLB NX pmd 0xffffffff82200000-0xffffffffa0000000 478M pmd Signed-off-by: Stephen Smalley Acked-by: Kees Cook Cc: Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1443704662-3138-1-git-send-email-sds@tycho.nsa.gov Signed-off-by: Ingo Molnar --- arch/x86/mm/init_64.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 30564e2752d3..df48430c279b 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1132,7 +1132,7 @@ void mark_rodata_ro(void) * has been zapped already via cleanup_highmem(). */ all_end = roundup((unsigned long)_brk_end, PMD_SIZE); - set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT); + set_memory_nx(text_end, (all_end - text_end) >> PAGE_SHIFT); rodata_test();