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SubjectRe: [PATCH v11 0/5] arm64: ARMv8.5-A: MTE: Add async mode support
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On 1/30/21 4:52 PM, Vincenzo Frascino 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.
>

We are suspecting an issue with with the kernel access nofault functions
triggering async faults that impacts Android init process.
Please do not merge this series until this is sorted.

> 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/v10.async.akpm
>
> Changes:
> --------
> v11:
> - Added patch that disables KUNIT tests in async mode
> v10:
> - Rebase on the latest linux-next/akpm
> - Address review comments.
> v9:
> - Rebase on the latest linux-next/akpm
> - Address review comments.
> v8:
> - Address review comments.
> v7:
> - Fix a warning reported by kernel test robot. This
> time for real.
> v6:
> - Drop patches that forbid KASAN KUNIT tests when async
> mode is enabled.
> - Fix a warning reported by kernel test robot.
> - Address review comments.
> v5:
> - Rebase the series on linux-next/akpm.
> - Forbid execution for KASAN KUNIT tests when async
> mode is enabled.
> - Dropped patch to inline mte_assign_mem_tag_range().
> - Address review comments.
> v4:
> - Added support for kasan.mode (sync/async) kernel
> command line parameter.
> - Addressed review comments.
> v3:
> - Exposed kasan_hw_tags_mode to convert the internal
> KASAN represenetation.
> - Added dsb() for kernel exit paths in arm64.
> - Addressed review comments.
> v2:
> - Fixed a compilation issue reported by krobot.
> - General cleanup.
>
> 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@google.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
>
> Andrey Konovalov (1):
> kasan: don't run tests in async mode
>
> Vincenzo Frascino (4):
> arm64: mte: Add asynchronous mode support
> kasan: Add KASAN mode kernel parameter
> kasan: Add report for async mode
> arm64: mte: Enable async tag check fault
>
> Documentation/dev-tools/kasan.rst | 9 +++++
> arch/arm64/include/asm/memory.h | 3 +-
> arch/arm64/include/asm/mte-kasan.h | 9 ++++-
> arch/arm64/include/asm/mte.h | 32 ++++++++++++++++
> arch/arm64/kernel/entry-common.c | 6 +++
> arch/arm64/kernel/mte.c | 60 +++++++++++++++++++++++++++++-
> include/linux/kasan.h | 6 +++
> lib/test_kasan.c | 6 ++-
> mm/kasan/hw_tags.c | 51 ++++++++++++++++++++++++-
> mm/kasan/kasan.h | 7 +++-
> mm/kasan/report.c | 17 ++++++++-
> 11 files changed, 196 insertions(+), 10 deletions(-)
>

--
Regards,
Vincenzo

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