linux-kernel - Re: [PATCH v7 1/3] x86/boot: Add acpitb.c to parse acpi tables

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Date:   Sat, 22 Sep 2018 08:45:12 -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 1/3] x86/boot: Add acpitb.c to parse acpi tables

On Thu, Sep 13, 2018 at 3:46 AM, Chao Fan <fanc.fnst@...fujitsu.com> wrote:
> There is a bug that kaslr may randomly chooses some positions
> which are located in movable memory regions. This will break memory
> hotplug feature and make the movable memory chosen by KASLR can't be
> removed. So dig SRAT table from ACPI tables to get memory information.
>
> Imitate the ACPI code of parsing ACPI tables to dig and read ACPI
> tables. Since some operations are not needed here, functions are
> simplified. Functions will be used to dig only SRAT tables to get
> information of memory, so that KASLR can the memory in immovable node.
>
> And also, these functions won't influence the initialization of
> ACPI after start_kernel().
>
> Since use physical address directely, so acpi_os_map_memory()
> and acpi_os_unmap_memory() are not needed.
>
> Signed-off-by: Chao Fan <fanc.fnst@...fujitsu.com>
> ---
>  arch/x86/boot/compressed/Makefile |   4 +
>  arch/x86/boot/compressed/acpitb.c | 401 ++++++++++++++++++++++++++++++

Does this logic live anywhere else in the kernel already? (i.e. could
other code be reused?)

-Kees

-- 
Kees Cook
Pixel Security