Messages in this thread | | | Date | Wed, 29 Sep 2021 16:49:08 +0100 | From | Will Deacon <> | Subject | Re: [PATCH 0/5] arm64: ARMv8.7-A: MTE: Add asymm mode support |
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On Mon, Sep 13, 2021 at 09:14:19AM +0100, Vincenzo Frascino wrote: > This series implements the asymmetric mode support for ARMv8.7-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. > > When asymmetric mode is present, the CPU triggers a fault on a tag mismatch > during a load operation and asynchronously updates a register when a tag > mismatch is detected during a store operation. > > The series is based on linux-v5.15-rc1. > > 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/v1.asymm > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> > Cc: Alexander Potapenko <glider@google.com> > Cc: Marco Elver <elver@google.com> > Cc: Evgenii Stepanov <eugenis@google.com> > Cc: Branislav Rankov <Branislav.Rankov@arm.com> > Cc: Andrey Konovalov <andreyknvl@gmail.com> > Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > > Vincenzo Frascino (5): > kasan: Remove duplicate of kasan_flag_async > arm64: mte: Bitfield definitions for Asymm MTE > arm64: mte: CPU feature detection for Asymm MTE > arm64: mte: Add asymmetric mode support > kasan: Extend KASAN mode kernel parameter > > Documentation/dev-tools/kasan.rst | 10 ++++++++--
I'm surprised not to see any update to:
Documentation/arm64/memory-tagging-extension.rst
particularly regarding the per-cpu preferred tag checking modes. Is asymmetric mode not supported there?
Will
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