Re: [PATCH RFC v2 14/21] kasan: add and integrate kasan boot parameters

[Marco Elver]

On Thu, 22 Oct 2020 at 15:19, Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote:
>
> TODO: no meaningful description here yet, please see the cover letter
>       for this RFC series.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Link: https://linux-review.googlesource.com/id/If7d37003875b2ed3e0935702c8015c223d6416a4
> ---
>  mm/kasan/common.c  |  92 +++++++++++++-----------
>  mm/kasan/generic.c |   5 ++
>  mm/kasan/hw_tags.c | 169 ++++++++++++++++++++++++++++++++++++++++++++-
>  mm/kasan/kasan.h   |   9 +++
>  mm/kasan/report.c  |  14 +++-
>  mm/kasan/sw_tags.c |   5 ++
>  6 files changed, 250 insertions(+), 44 deletions(-)
>
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 1a5e6c279a72..cc129ef62ab1 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -129,35 +129,37 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
>         unsigned int redzone_size;
>         int redzone_adjust;
>
> -       /* Add alloc meta. */
> -       cache->kasan_info.alloc_meta_offset = *size;
> -       *size += sizeof(struct kasan_alloc_meta);
> -
> -       /* Add free meta. */
> -       if (IS_ENABLED(CONFIG_KASAN_GENERIC) &&
> -           (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor ||
> -            cache->object_size < sizeof(struct kasan_free_meta))) {
> -               cache->kasan_info.free_meta_offset = *size;
> -               *size += sizeof(struct kasan_free_meta);
> -       }
> -
> -       redzone_size = optimal_redzone(cache->object_size);
> -       redzone_adjust = redzone_size - (*size - cache->object_size);
> -       if (redzone_adjust > 0)
> -               *size += redzone_adjust;
> -
> -       *size = min_t(unsigned int, KMALLOC_MAX_SIZE,
> -                       max(*size, cache->object_size + redzone_size));
> +       if (static_branch_unlikely(&kasan_stack)) {

I just looked at this file in your Github repo, and noticed that this
could just be

if (!static_branch_unlikely(&kasan_stack))
    return;

since the if-block ends at the function. That might hopefully make the
diff a bit smaller.

Thanks,
-- Marco