[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <808ed933-fbc6-4ace-812c-08170b51d699@amperemail.onmicrosoft.com>
Date: Tue, 10 Dec 2024 17:47:05 +0800
From: Shijie Huang <shijie@...eremail.onmicrosoft.com>
To: Anshuman Khandual <anshuman.khandual@....com>,
Ard Biesheuvel <ardb@...nel.org>
Cc: Huang Shijie <shijie@...amperecomputing.com>, catalin.marinas@....com,
will@...nel.org, corbet@....net, patches@...erecomputing.com, cl@...ux.com,
akpm@...ux-foundation.org, thuth@...hat.com, rostedt@...dmis.org,
xiongwei.song@...driver.com, inux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 1/2] arm64: refactor the rodata=xxx
On 2024/12/10 16:38, Anshuman Khandual wrote:
>
> On 12/10/24 12:51, Ard Biesheuvel wrote:
>> On Tue, 10 Dec 2024 at 08:17, Anshuman Khandual
>> <anshuman.khandual@....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'?
> Right, the last sentence can be can dropped.
Okay, no problem.
Thanks
Huang Shijie
Powered by blists - more mailing lists