Re: [PATCH] kaslr: rename physmem_end and PHYSMEM_END to direct_map_physmem_end

[Will Deacon]

On Tue, Oct 08, 2024 at 07:50:24PM -0700, 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@xxxxxxxxxxxxx>
> Cc: Alistair Popple <apopple@xxxxxxxxxx>
> Cc: Jordan Niethe <jniethe@xxxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
> ---
> 
> 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.
> 
> 
> [1] https://lore.kernel.org/linux-mm/ee205448-5fdd-495e-9d7c-c8a2b59f9c9e@xxxxxxxxxxxx/T/#mdf442f077c9023590e144dbed2b04a109793484d
> 
> thanks,
> John Hubbard
> 
> 
>  arch/arm64/include/asm/memory.h         |  2 +-
>  arch/x86/include/asm/page_64.h          |  2 +-
>  arch/x86/include/asm/pgtable_64_types.h |  2 +-
>  arch/x86/mm/init_64.c                   |  2 +-
>  arch/x86/mm/kaslr.c                     | 14 +++++++++-----
>  include/linux/mm.h                      |  6 +++---
>  kernel/resource.c                       |  4 ++--
>  mm/memory_hotplug.c                     |  2 +-
>  mm/sparse.c                             |  2 +-
>  9 files changed, 20 insertions(+), 16 deletions(-)

For arm64:

Acked-by: Will Deacon <will@xxxxxxxxxx>

Will