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Date: Tue, 9 Aug 2016 11:23:07 +0200 (CEST)
From: Jiri Kosina <>
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, 8 Aug 2016, 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 <>
> 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?

Unfortunately this applied on top of -rc1 still doesn't solve the reboot 
after reading hibernation image (I'd guess due to triple fault) with 

With CONFIG_RANDOMIZE_MEMORY=n, the system resumes correctly.

Jiri Kosina

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