linux-kernel - Re: [PATCH v12 6/7] arm64: mte: Save/Restore TFSR

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Date:   Tue, 9 Feb 2021 18:25:31 +0000
From:   Vincenzo Frascino <vincenzo.frascino@....com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        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>
Subject: Re: [PATCH v12 6/7] arm64: mte: Save/Restore TFSR_EL1 during suspend

On 2/9/21 5:28 PM, Catalin Marinas wrote:
>> I don't think though you can "check" with IRQs disabled so I suspect
>> that TFSR_EL1 has to be saved/restored (which means that there is a
>> black out period where we run kernel code without being able to detect
>> faults but there is no solution to that other than delaying saving the
>> value to just before calling into PSCI). Likewise on resume from low
>> power.
> It depends on whether kasan_report can be called with IRQs disabled. I
> don't see why not, so if this works I'd rather just call mte_check_async
> (or whatever it's called) on the suspend path and zero the register on
> resume (mte_suspend_exit). We avoid any saving of the state.

Fine by me, I tried a quick test and can confirm that kasan_report can be
invoked with IRQ disabled.

-- 
Regards,
Vincenzo