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Message-ID: <alpine.LNX.2.00.1608091702240.22028@cbobk.fhfr.pm>
Date: Tue, 9 Aug 2016 17:05:36 +0200 (CEST)
From: Jiri Kosina <jikos@...nel.org>
To: Thomas Garnier <thgarnie@...gle.com>
cc: "Rafael J. Wysocki" <rafael@...nel.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Linux PM list <linux-pm@...r.kernel.org>,
the arch/x86 maintainers <x86@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Yinghai Lu <yinghai@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>,
Kees Cook <keescook@...omium.org>, Pavel Machek <pavel@....cz>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>,
Borislav Petkov <bpetkov@...e.de>
Subject: Re: [Resend][PATCH] x86/power/64: Always create temporary identity
mapping correctly
On Tue, 9 Aug 2016, Thomas Garnier wrote:
> >> Okay, I did one-by-one reverts, and the one above, i.e.
> >>
> >> commit 021182e52fe01c1f7b126f97fd6ba048dc4234fd
> >> Author: Thomas Garnier <thgarnie@...gle.com>
> >> Date: Tue Jun 21 17:47:03 2016 -0700
> >>
> >> x86/mm: Enable KASLR for physical mapping memory regions
> >>
> >> is the one that is the culprit on my machine. With this one reverted,
> >> resume hibernation doesn't reboot (tripple fault?), but proceeds
> >> succesfully.
>
> My .config is attached. It is basically defconfig (x86_64) + kvmconfig
> plus the following:
>
> CONFIG_PHYSICAL_START=0x1000000
> CONFIG_RELOCATABLE=y
> CONFIG_RANDOMIZE_BASE=y
> CONFIG_X86_NEED_RELOCS=y
> CONFIG_PHYSICAL_ALIGN=0x1000000
> CONFIG_RANDOMIZE_MEMORY=y
> CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING=0xa
> CONFIG_X86_PTDUMP_CORE=y
> CONFIG_X86_PTDUMP=y
> CONFIG_KALLSYMS=y
> CONFIG_KALLSYMS_ALL=y
> CONFIG_KALLSYMS_ABSOLUTE_PERCPU=y
> CONFIG_KALLSYMS_BASE_RELATIVE=y
> CONFIG_PANIC_ON_OOPS=y
> CONFIG_KGDB=y
> CONFIG_EARLY_PRINTK=y
> CONFIG_EARLY_PRINTK_DBGP=y
> CONFIG_DEBUG_INFO=y
> CONFIG_DEBUG_INFO_DWARF4=y
The config I am reproducing the bug with (on thinkpad x200s) can be found
at
http://www.jikos.cz/jikos/junk/.config
Either later today or tomorrow I could test with the same physical start
and align values you're using to see whether that'd make any difference.
> > As discussed with Rafael privately, I also tried this very patch
> > (x86/power/64: Always create temporary identity mapping correctly) on top
> > of the reverted revert of 021182e52fe01c1f7b1 (see the full log below),
> > but such kernel triple faults on resume as well.
> >
> > 87c38d2 x86/power/64: Always create temporary identity mapping correctly
> > 3cb504a Revert "Revert "x86/mm: Enable KASLR for physical mapping memory regions""
> > 758850d Revert "x86/mm: Enable KASLR for physical mapping memory regions"
> > 4a02dfb Revert "x86/mm: Enable KASLR for vmalloc memory regions"
> > 037863f Revert "x86/mm: Add memory hotplug support for KASLR memory randomization"
> > 3416a21 Revert "x86/mm: Do not reference phys addr beyond kernel"
> > 69227be Revert "mm: reorganize SLAB freelist randomization"
> > a1d8d71 Revert "mm: SLUB freelist randomization"
> >
> > IOW, 021182e52f introduces a bug for which there is no existing fix yet.
>
> You mean it is something different from the previous KASLR bugs we saw?
No, I just wanted to explicitly point out that "x86/power/64: Always
create temporary identity mapping correctly" is not a fix for this issue.
--
Jiri Kosina
SUSE Labs
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