linux-kernel - Re: [PATCH v7 2/3] x86/boot/KASLR: Walk srat tables to filter immovable memory

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Message-ID: <CAGXu5j+amHGGCxC9PVrCfV8qNchyAyxd225F1rW2o2t=NRogDg@mail.gmail.com>
Date:   Sat, 22 Sep 2018 08:46:22 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Chao Fan <fanc.fnst@...fujitsu.com>
Cc:     linux-efi <linux-efi@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, Baoquan He <bhe@...hat.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        indou.takao@...fujitsu.com, caoj.fnst@...fujitsu.com
Subject: Re: [PATCH v7 2/3] x86/boot/KASLR: Walk srat tables to filter
 immovable memory

On Thu, Sep 13, 2018 at 3:46 AM, Chao Fan <fanc.fnst@...fujitsu.com> wrote:
> If CONFIG_MEMORY_HOTREMOVE enabled, walk through the acpi srat memory
> tables and store those immovable memory regions so that kaslr can get
> where to choose for randomization.
>
> Signed-off-by: Chao Fan <fanc.fnst@...fujitsu.com>
> ---
>  arch/x86/boot/compressed/kaslr.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> index 9ed9709d9947..0c3567bc231c 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -417,6 +417,11 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
>         /* Mark the memmap regions we need to avoid */
>         handle_mem_options();
>
> +#ifdef CONFIG_MEMORY_HOTREMOVE
> +       /* Mark the immovable regions we need to choose */
> +       get_immovable_mem();
> +#endif

Style nit-pick: I'd prefer the definition of get_immovable_mem() do
the ifdef so it doesn't appear here.

-Kees

> +
>  #ifdef CONFIG_X86_VERBOSE_BOOTUP
>         /* Make sure video RAM can be used. */
>         add_identity_map(0, PMD_SIZE);
> --
> 2.17.1
>
>
>



-- 
Kees Cook
Pixel Security