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

Chao Fan
2018-09-25T01:13:24Z

On Sat, Sep 22, 2018 at 08:45:12AM -0700, Kees Cook wrote:
>On Thu, Sep 13, 2018 at 3:46 AM, Chao Fan <fanc.fnst@cn.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@cn.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?)

Live in uncompressec period, but not completely same.
The map between physical address and virtual address is not needed here.
So I thins it's hard to reuse, that's why I made this new file.

Thanks,
Chao Fan

>
>-Kees
>
>--
>Kees Cook
>Pixel Security
>
>