linux-kernel - Re: [RFC 21/43] x86/KASLR: PKRAM: support physical kaslr

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Message-ID: <62a1c002-ad7b-a364-5797-6d7f5545d5cf@oracle.com>
Date:   Thu, 7 May 2020 11:41:51 -0700
From:   Anthony Yznaga <anthony.yznaga@...cle.com>
To:     Kees Cook <keescook@...omium.org>
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Subject: Re: [RFC 21/43] x86/KASLR: PKRAM: support physical kaslr



On 5/7/20 10:51 AM, Kees Cook wrote:
> On Wed, May 06, 2020 at 05:41:47PM -0700, Anthony Yznaga wrote:
>> Avoid regions of memory that contain preserved pages when computing
>> slots used to select where to put the decompressed kernel.
> This is changing the slot-walking code instead of updating
> mem_avoid_overlap() -- that's where the check for a "reserved" memory
> area should live.
>
> For example, this is how both mem_avoid_memmap() and the setup_data
> memory areas are handled.
>
> Is there a reason mem_avoid_overlap() can't be used here?
>

I was thinking it would be more efficient to process just
the regions that did not contain preserved pages rather
than checking for preserved pages in mem_avoid_overlap(),
but I see that may just be adding unnecessary complexity.
I'll investigate modifying mem_avoid_overlap().
Thank you for the comments!

Anthony