Re: [PATCH v2 00/12] kasan: optimizations and fixes for HW_TAGS

From: Andrey Konovalov
Date: Fri Feb 05 2021 - 17:06:35 EST


On Fri, Feb 5, 2021 at 4:39 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> 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@xxxxxxx/
> [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
>