linux-kernel - Re: [PATCH v8 1/2] kasan/hw-tags: introduce kasan.write

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Message-ID: <dcd0c9be-5a52-480e-8447-ebb0a028edec@gmail.com>
Date: Thu, 18 Sep 2025 16:47:33 +0200
From: Andrey Ryabinin <ryabinin.a.a@...il.com>
To: Yeoreum Yun <yeoreum.yun@....com>, glider@...gle.com,
 andreyknvl@...il.com, dvyukov@...gle.com, vincenzo.frascino@....com,
 corbet@....net, catalin.marinas@....com, will@...nel.org,
 akpm@...ux-foundation.org, scott@...amperecomputing.com,
 jhubbard@...dia.com, pankaj.gupta@....com, leitao@...ian.org,
 kaleshsingh@...gle.com, maz@...nel.org, broonie@...nel.org,
 oliver.upton@...ux.dev, james.morse@....com, ardb@...nel.org,
 hardevsinh.palaniya@...iconsignals.io, david@...hat.com,
 yang@...amperecomputing.com
Cc: kasan-dev@...glegroups.com, workflows@...r.kernel.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org
Subject: Re: [PATCH v8 1/2] kasan/hw-tags: introduce kasan.write_only option



On 9/17/25 12:27 AM, Yeoreum Yun wrote:
> Since Armv8.9, FEATURE_MTE_STORE_ONLY feature is introduced to restrict
> raise of tag check fault on store operation only.
> Introduce KASAN write only mode based on this feature.
> 
> KASAN write only mode restricts KASAN checks operation for write only and
> omits the checks for fetch/read operations when accessing memory.
> So it might be used not only debugging enviroment but also normal
> enviroment to check memory safty.
> 
> This features can be controlled with "kasan.write_only" arguments.
> When "kasan.write_only=on", KASAN checks write operation only otherwise
> KASAN checks all operations.
> 
> This changes the MTE_STORE_ONLY feature as BOOT_CPU_FEATURE like
> ARM64_MTE_ASYMM so that makes it initialise in kasan_init_hw_tags()
> with other function together.
> 
> Signed-off-by: Yeoreum Yun <yeoreum.yun@....com>
> Reviewed-by: Catalin Marinas <catalin.marinas@....com>

Reviewed-by: Andrey Ryabinin <ryabinin.a.a@...il.com>