linux-kernel - Re: [PATCH v6 1/2] kasan/hw-tags: introduce kasan.write

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Message-Id: <20250901122316.6b7d8d7fdcf03bdb2aa4960a@linux-foundation.org>
Date: Mon, 1 Sep 2025 12:23:16 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Yeoreum Yun <yeoreum.yun@....com>
Cc: ryabinin.a.a@...il.com, glider@...gle.com, andreyknvl@...il.com,
 dvyukov@...gle.com, vincenzo.frascino@....com, corbet@....net,
 catalin.marinas@....com, will@...nel.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, 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 v6 1/2] kasan/hw-tags: introduce kasan.write_only option

On Mon,  1 Sep 2025 11:46:22 +0100 Yeoreum Yun <yeoreum.yun@....com> wrote:

> Since Armv8.9, FEATURE_MTE_STORE_ONLY feature is introduced to restrict
> raise of tag check fault on store operation only.
> Introcude 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.
> 
> ...
>
>  
> -	pr_info("KernelAddressSanitizer initialized (hw-tags, mode=%s, vmalloc=%s, stacktrace=%s)\n",
> +	pr_info("KernelAddressSanitizer initialized (hw-tags, mode=%s, vmalloc=%s, stacktrace=%s, write_only=%s\n",
>  		kasan_mode_info(),

This lost the closing ")" in the printk control string.  I fixed that
up while resolving rejects.