linux-kernel - Re: [Resend][PATCH] x86/power/64: Always create temporary identity mapping correctly

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Message-ID: <alpine.LNX.2.00.1608091525540.22028@cbobk.fhfr.pm>
Date:	Tue, 9 Aug 2016 15:30:04 +0200 (CEST)
From:	Jiri Kosina <jikos@...nel.org>
To:	"Rafael J. Wysocki" <rafael@...nel.org>
cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Thomas Garnier <thgarnie@...gle.com>,
	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, Jiri Kosina wrote:

> > 210e7a43fa90 mm: SLUB freelist randomization
> > 7c00fce98c3e mm: reorganize SLAB freelist randomization
> > 4ff5308744f5 x86/mm: Do not reference phys addr beyond kernel
> > 90397a417796 x86/mm: Add memory hotplug support for KASLR memory randomization
> > a95ae27c2ee1 x86/mm: Enable KASLR for vmalloc memory regions
> > 021182e52fe0 x86/mm: Enable KASLR for physical mapping memory regions
> 
> 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.

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.

-- 
Jiri Kosina
SUSE Labs