linux-kernel - Re: [PATCH 22/35] arm64: mte: Enable in-kernel MTE

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Message-ID: <20200827100155.GD29264@gaia>
Date:   Thu, 27 Aug 2020 11:01:56 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Andrey Konovalov <andreyknvl@...gle.com>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        kasan-dev@...glegroups.com,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Elena Petrova <lenaptr@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        Will Deacon <will.deacon@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 22/35] arm64: mte: Enable in-kernel MTE

On Fri, Aug 14, 2020 at 07:27:04PM +0200, Andrey Konovalov wrote:
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 4d3abb51f7d4..4d94af19d8f6 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -1670,6 +1670,9 @@ static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
>  	write_sysreg_s(0, SYS_TFSR_EL1);
>  	write_sysreg_s(0, SYS_TFSRE0_EL1);
>  
> +	/* Enable Match-All at EL1 */
> +	sysreg_clear_set(tcr_el1, 0, SYS_TCR_EL1_TCMA1);
> +
>  	/*
>  	 * CnP must be enabled only after the MAIR_EL1 register has been set
>  	 * up. Inconsistent MAIR_EL1 between CPUs sharing the same TLB may
> @@ -1687,6 +1690,9 @@ static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
>  	mair &= ~MAIR_ATTRIDX(MAIR_ATTR_MASK, MT_NORMAL_TAGGED);
>  	mair |= MAIR_ATTRIDX(MAIR_ATTR_NORMAL_TAGGED, MT_NORMAL_TAGGED);
>  	write_sysreg_s(mair, SYS_MAIR_EL1);
> +
> +	/* Enable MTE Sync Mode for EL1 */
> +	sysreg_clear_set(sctlr_el1, SCTLR_ELx_TCF_MASK, SCTLR_ELx_TCF_SYNC);

In the 8th incarnation of the user MTE patches, this initialisation
moved to proc.S before the MMU is initialised. When rebasing, please
take this into account.

-- 
Catalin