From: Ingo Molnar <mingo@kernel.org>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>,
Kees Cook <keescook@chromium.org>, Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org, Andy Lutomirski <luto@kernel.org>,
Borislav Petkov <bp@alien8.de>,
Denys Vlasenko <dvlasenk@redhat.com>,
Brian Gerst <brgerst@gmail.com>
Subject: Re: PROBLEM: Resume form hibernate broken by setting NX on gap
Date: Fri, 20 May 2016 09:15:17 +0200 [thread overview]
Message-ID: <20160520071517.GB14191@gmail.com> (raw)
In-Reply-To: <573DF82D.50006@deltatee.com>
* Logan Gunthorpe <logang@deltatee.com> 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 <sds@tycho.nsa.gov>
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 <sds@tycho.nsa.gov>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: <stable@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
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 <mingo@kernel.org>
---
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();
next parent reply other threads:[~2016-05-20 7:15 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <573DF82D.50006@deltatee.com>
2016-05-20 7:15 ` Ingo Molnar [this message]
2016-05-20 11:34 ` PROBLEM: Resume form hibernate broken by setting NX on gap Rafael J. Wysocki
2016-05-20 13:56 ` Stephen Smalley
2016-05-20 21:46 ` Rafael J. Wysocki
2016-05-20 21:59 ` Kees Cook
2016-05-20 22:16 ` Kees Cook
[not found] ` <573FC081.20006@deltatee.com>
2016-05-21 16:39 ` Kees Cook
[not found] ` <575A3E95.5090100@deltatee.com>
2016-06-10 18:09 ` Kees Cook
2016-06-10 18:16 ` Logan Gunthorpe
2016-06-10 18:18 ` Kees Cook
2016-06-10 21:27 ` Rafael J. Wysocki
2016-06-10 22:29 ` Rafael J. Wysocki
2016-06-10 22:28 ` Logan Gunthorpe
2016-06-10 22:33 ` Rafael J. Wysocki
2016-06-11 0:13 ` Rafael J. Wysocki
2016-06-11 1:47 ` Rafael J. Wysocki
2016-06-11 11:48 ` Rafael J. Wysocki
2016-06-11 16:35 ` Logan Gunthorpe
2016-06-11 17:39 ` Logan Gunthorpe
2016-06-12 1:05 ` Rafael J. Wysocki
2016-06-12 4:48 ` Logan Gunthorpe
2016-06-12 14:31 ` Rafael J. Wysocki
2016-06-12 16:11 ` Logan Gunthorpe
2016-06-13 13:43 ` Rafael J. Wysocki
2016-06-10 22:11 ` Rafael J. Wysocki
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