linux-kernel - Re: [PATCH v2 00/12] kasan: optimizations and fixes for HW

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Date:   Fri, 5 Feb 2021 17:25:44 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>
Cc:     Will Deacon <will.deacon@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 00/12] kasan: optimizations and fixes for HW_TAGS

On Fri, Feb 5, 2021 at 4:39 PM Andrey Konovalov <andreyknvl@...gle.com> wrote:
>
> This patchset goes on top of:
>
> 1. Vincenzo's async support patches [1], and
> 2. "kasan: untag addresses for KFENCE" fix [2] (already in mm).
>
> [1] https://lore.kernel.org/linux-arm-kernel/20210130165225.54047-1-vincenzo.frascino@arm.com/
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=akpm&id=dec4728fab910da0c86cf9a97e980f4244ebae9f
>
> This patchset makes the HW_TAGS mode more efficient, mostly by reworking
> poisoning approaches and simplifying/inlining some internal helpers.
>
> With this change, the overhead of HW_TAGS annotations excluding setting
> and checking memory tags is ~3%. The performance impact caused by tags
> will be unknown until we have hardware that supports MTE.
>
> As a side-effect, this patchset speeds up generic KASAN by ~15%.

Forgot to include changes v1->v2:

- Use EXPORT_SYMBOL_GPL() for arm64 symbols.
- Rename kmalloc bool flag argument to is_kmalloc.
- Make empty mte_set_mem_tag_range() return void.
- Fix build warning in 32-bit systems by using unsigned long instead
of u64 in WARN_ON() checks.
- Minor changes in comments and commit descriptions.
- Use kfence_ksize() before __ksize() to avoid crashes with KFENCE.
- Use inline instead of __always_inline.

>
> Andrey Konovalov (12):
>   kasan, mm: don't save alloc stacks twice
>   kasan, mm: optimize kmalloc poisoning
>   kasan: optimize large kmalloc poisoning
>   kasan: clean up setting free info in kasan_slab_free
>   kasan: unify large kfree checks
>   kasan: rework krealloc tests
>   kasan, mm: fail krealloc on freed objects
>   kasan, mm: optimize krealloc poisoning
>   kasan: ensure poisoning size alignment
>   arm64: kasan: simplify and inline MTE functions
>   kasan: inline HW_TAGS helper functions
>   arm64: kasan: export MTE symbols for KASAN tests
>
>  arch/arm64/include/asm/cache.h     |   1 -
>  arch/arm64/include/asm/kasan.h     |   1 +
>  arch/arm64/include/asm/mte-def.h   |   2 +
>  arch/arm64/include/asm/mte-kasan.h |  65 ++++++++--
>  arch/arm64/include/asm/mte.h       |   2 -
>  arch/arm64/kernel/mte.c            |  48 +-------
>  arch/arm64/lib/mte.S               |  16 ---
>  include/linux/kasan.h              |  25 ++--
>  lib/test_kasan.c                   | 111 +++++++++++++++--
>  mm/kasan/common.c                  | 187 ++++++++++++++++++++---------
>  mm/kasan/kasan.h                   |  72 +++++++++--
>  mm/kasan/shadow.c                  |  53 ++++----
>  mm/slab_common.c                   |  18 ++-
>  mm/slub.c                          |   3 +-
>  14 files changed, 418 insertions(+), 186 deletions(-)
>
> --
> 2.30.0.365.g02bc693789-goog
>