Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210308161434.33424-1-vincenzo.frascino@arm.com>
In-Reply-To: <20210308161434.33424-1-vincenzo.frascino@arm.com>
From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Mon, 8 Mar 2021 22:02:25 +0100
Message-ID: <CAAeHK+xEc8spQWh9Mz7z-mVQRavD2y84ufnGx6cm-gK3AkJfAw@mail.gmail.com>
Subject: Re: [PATCH v14 0/8] arm64: ARMv8.5-A: MTE: Add async mode support
To:     Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc:     Linux ARM <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        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>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Mar 8, 2021 at 5:14 PM Vincenzo Frascino
<vincenzo.frascino@arm.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!