linux-kernel - Re: [PATCH v14 5/8] arm64: mte: Enable TCO in functions that can read beyond buffer limits

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Message-ID: <42b39ecc-4f97-63bf-cdab-2ba4817b8610@arm.com>
Date:   Tue, 9 Mar 2021 10:26:54 +0000
From:   Vincenzo Frascino <vincenzo.frascino@....com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Subject: Re: [PATCH v14 5/8] arm64: mte: Enable TCO in functions that can read
 beyond buffer limits

On 3/8/21 6:09 PM, Mark Rutland wrote:
>> +DECLARE_STATIC_KEY_FALSE(mte_async_mode);
> Can we please hide this behind something like:
> 
> static inline bool system_uses_mte_async_mode(void)
> {
> 	return IS_ENABLED(CONFIG_KASAN_HW_TAGS) &&
> 		static_branch_unlikely(&mte_async_mode);
> }
> 
> ... like we do for system_uses_ttbr0_pan()?
>

I agree, it is a cleaner solution. I will add it to v15.

> That way the callers are easier to read, and kernels built without
> CONFIG_KASAN_HW_TAGS don't have the static branch at all. I reckon you
> can put that in one of hte mte headers and include it where needed.

-- 
Regards,
Vincenzo