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Date: Mon, 8 Aug 2016 15:40:01 +0200
From: Borislav Petkov <>
To: "Rafael J. Wysocki" <>
Cc: Linux PM list <>,
	Thomas Garnier <>,
	the arch/x86 maintainers <>,
	Linux Kernel Mailing List <>,
	Yinghai Lu <>,
	Thomas Gleixner <>,
	Ingo Molnar <>, "H . Peter Anvin" <>,
	Kees Cook <>, Pavel Machek <>,
	Kernel Hardening <>,
	Borislav Petkov <>
Subject: Re: [Resend][PATCH] x86/power/64: Always create temporary identity
 mapping correctly

On Mon, Aug 08, 2016 at 03:31:31PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <>
> The low-level resume-from-hibernation code on x86-64 uses
> kernel_ident_mapping_init() to create the temoprary identity mapping,
> but that function assumes that the offset between kernel virtual
> addresses and physical addresses is aligned on the PGD level.
> However, with a randomized identity mapping base, it may be aligned
> on the PUD level and if that happens, the temporary identity mapping
> created by set_up_temporary_mappings() will not reflect the actual
> kernel identity mapping and the image restoration will fail as a
> result (leading to a kernel panic most of the time).
> To fix this problem, rework kernel_ident_mapping_init() to support
> unaligned offsets between KVA and PA up to the PMD level and make
> set_up_temporary_mappings() use it as approprtiate.
> Reported-by: Thomas Garnier <>

Reported-by: Borislav Petkov <>

> Suggested-by: Yinghai Lu <>
> Signed-off-by: Rafael J. Wysocki <>
> Acked-by: Yinghai Lu <>
> ---
> This is sort of urgent, because hibernation doesn't work with KASLR on x86-64
> in 4.8-rc1 AFAICS and this should make them work together again.
> Unless anyone sees any problems with it, I'll queue it up for 4.8-rc2.
> Thomas, would it be possible to test it with KASLR enabled, please?

Is that the only patch which needs to be tested? Ontop of which tree?

CONFIG_RANDOMIZE_MEMORY blew up s2d on my laptop here so I'll run it
once I have the required info from you :)



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