[PATCH v3 1/2] arm64: refactor the rodata=xxx
Ard Biesheuvel
ardb at kernel.org
Mon Dec 9 23:21:56 PST 2024
On Tue, 10 Dec 2024 at 08:17, Anshuman Khandual
<anshuman.khandual at arm.com> wrote:
>
...
>
> Reformatted and cleaned up the above comment a bit but feel free to
> improve it further.
>
> /*
> * rodata=on (default)
> *
> * This applies read-only attributes to VM areas and to the linear
> * alias of the backing pages as well. This prevents code or read-
> * only data from being modified (inadvertently or intentionally),
> * via another mapping for the same memory page.
> *
> * But this might cause linear map region to be mapped down to base
> * pages, which may adversely affect performance in some cases.
> *
> * rodata=off
> *
> * This provides more block mappings and contiguous hints for linear
> * map region which would minimize TLB footprint. This also leaves
> * read-only kernel memory writable for debugging.
> *
> * rodata=noalias
> *
> * This provides more block mappings and contiguous hints for linear
> * map region which would minimize TLB footprint. Linear aliases of
> * pages belonging to read-only mappings in vmalloc region are also
> * marked as read-only.
>
If linear aliases are marked as read-only, how does 'noalias' differ from 'on'?
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