[PATCH 0/5] arm64: ARMv8.7-A: MTE: Add asymm mode support

[Vincenzo Frascino]

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@xxxxxxxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>

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 ++++++++--
 arch/arm64/include/asm/memory.h    |  1 +
 arch/arm64/include/asm/mte-kasan.h |  5 +++++
 arch/arm64/include/asm/sysreg.h    |  3 +++
 arch/arm64/kernel/cpufeature.c     | 10 ++++++++++
 arch/arm64/kernel/mte.c            | 26 ++++++++++++++++++++++++++
 arch/arm64/tools/cpucaps           |  1 +
 mm/kasan/hw_tags.c                 | 27 ++++++++++++++++++++++-----
 mm/kasan/kasan.h                   |  7 +++++--
 9 files changed, 81 insertions(+), 9 deletions(-)

-- 
2.33.0