linux-kernel - Re: [PATCH] kaslr: rename physmem_end and PHYSMEM_END to direct_map_physmem

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Message-ID: <38b5649b-0e4b-460c-8097-04c530fbfa46@redhat.com>
Date: Mon, 14 Oct 2024 13:46:04 +0200
From: David Hildenbrand <david@...hat.com>
To: John Hubbard <jhubbard@...dia.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: Thomas Gleixner <tglx@...utronix.de>, Will Deacon <will@...nel.org>,
 Alistair Popple <apopple@...dia.com>, Jordan Niethe <jniethe@...dia.com>,
 linux-arm-kernel@...ts.infradead.org, x86@...nel.org, linux-mm@...ck.org,
 LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kaslr: rename physmem_end and PHYSMEM_END to
 direct_map_physmem_end

On 09.10.24 04:50, John Hubbard wrote:
> For clarity. It's increasingly hard to reason about the code, when KASLR
> is moving around the boundaries. In this case where KASLR is randomizing
> the location of the kernel image within physical memory, the maximum
> number of address bits for physical memory has not changed.
> 
> What has changed is the ending address of memory that is allowed to be
> directly mapped by the kernel.
> 
> Let's name the variable, and the associated macro accordingly.
> 
> Also, enhance the comment above the direct_map_physmem_end definition,
> to further clarify how this all works.
> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Alistair Popple <apopple@...dia.com>
> Cc: Jordan Niethe <jniethe@...dia.com>
> Cc: David Hildenbrand <david@...hat.com>
> Signed-off-by: John Hubbard <jhubbard@...dia.com>
> ---
> 
> David Hildenbrand, I recall you had an unanswered question in this
> vicinity [1] when tglx's recent kaslr fix was being reviewed. Maybe this
> will help with that.

Yes, that makes it clearer for me, thanks

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb