linux-kernel - Re: [PATCH v14 0/8] arm64: ARMv8.5-A: MTE: Add async mode support

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Message-ID: <723ec86a-75be-e0e3-e4a9-b3d40d69e238@arm.com>
Date:   Tue, 9 Mar 2021 10:11:07 +0000
From:   Vincenzo Frascino <vincenzo.frascino@....com>
To:     Andrey Konovalov <andreyknvl@...gle.com>
Cc:     Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kasan-dev <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>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Subject: Re: [PATCH v14 0/8] arm64: ARMv8.5-A: MTE: Add async mode support

Hi Andrey,

On 3/8/21 9:02 PM, Andrey Konovalov wrote:
> On Mon, Mar 8, 2021 at 5:14 PM Vincenzo Frascino
> <vincenzo.frascino@....com> wrote:
>>
>> This patchset implements the asynchronous mode support for ARMv8.5-A
>> Memory Tagging Extension (MTE), which is a debugging feature that allows
>> to detect with the help of the architecture the C and C++ programmatic
>> memory errors like buffer overflow, use-after-free, use-after-return, etc.
>>
>> MTE is built on top of the AArch64 v8.0 virtual address tagging TBI
>> (Top Byte Ignore) feature and allows a task to set a 4 bit tag on any
>> subset of its address space that is multiple of a 16 bytes granule. MTE
>> is based on a lock-key mechanism where the lock is the tag associated to
>> the physical memory and the key is the tag associated to the virtual
>> address.
>> When MTE is enabled and tags are set for ranges of address space of a task,
>> the PE will compare the tag related to the physical memory with the tag
>> related to the virtual address (tag check operation). Access to the memory
>> is granted only if the two tags match. In case of mismatch the PE will raise
>> an exception.
>>
>> The exception can be handled synchronously or asynchronously. When the
>> asynchronous mode is enabled:
>>   - Upon fault the PE updates the TFSR_EL1 register.
>>   - The kernel detects the change during one of the following:
>>     - Context switching
>>     - Return to user/EL0
>>     - Kernel entry from EL1
>>     - Kernel exit to EL1
>>   - If the register has been updated by the PE the kernel clears it and
>>     reports the error.
>>
>> The series is based on linux-next/akpm.
>>
>> To simplify the testing a tree with the new patches on top has been made
>> available at [1].
>>
>> [1] https://git.gitlab.arm.com/linux-arm/linux-vf.git mte/v12.async.akpm
> 
> Hi Vincenzo,
> 
> As previously discussed, here's the tree with tests support added to
> this series:
> 
> https://github.com/xairy/linux/tree/vf-v12.async.akpm-tests
> 
> Please take a look at the last two patches. Feel free to include them
> into v15 if they look good.
> 
> Thanks!
> 

Thank you for this. I will definitely have a look and include them.
Based on the review process, I am planning to have another version early next week.

-- 
Regards,
Vincenzo