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Subject: Re: [PATCH v12 6/7] arm64: mte: Save/Restore TFSR_EL1 during suspend
To:     Catalin Marinas <catalin.marinas@arm.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc:     linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        kasan-dev@googlegroups.com,
        Andrew Morton <akpm@linux-foundation.org>,
        Will Deacon <will@kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Andrey Konovalov <andreyknvl@google.com>
References: <20210208165617.9977-1-vincenzo.frascino@arm.com>
 <20210208165617.9977-7-vincenzo.frascino@arm.com>
 <20210209115533.GE1435@arm.com>
 <20210209143328.GA27791@e121166-lin.cambridge.arm.com>
 <20210209172821.GI1435@arm.com>
From:   Vincenzo Frascino <vincenzo.frascino@arm.com>
Message-ID: <89c95a1e-cfd2-7840-3175-deaeb336190b@arm.com>
Date:   Tue, 9 Feb 2021 18:25:31 +0000
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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