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From:   Alexander Potapenko <glider@google.com>
Date:   Fri, 8 Dec 2023 17:51:51 +0100
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Subject: Re: [PATCH v2 09/33] kmsan: Introduce kmsan_memmove_metadata()
To:     Ilya Leoshkevich <iii@linux.ibm.com>
Cc:     Alexander Gordeev <agordeev@linux.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Marco Elver <elver@google.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Pekka Enberg <penberg@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>,
        kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-s390@vger.kernel.org,
        linux-trace-kernel@vger.kernel.org,
        Mark Rutland <mark.rutland@arm.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Sven Schnelle <svens@linux.ibm.com>
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On Tue, Nov 21, 2023 at 11:07=E2=80=AFPM Ilya Leoshkevich <iii@linux.ibm.co=
m> wrote:
>
> It is useful to manually copy metadata in order to describe the effects
> of memmove()-like logic in uninstrumented code or inline asm. Introduce
> kmsan_memmove_metadata() for this purpose.
>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>  include/linux/kmsan-checks.h | 14 ++++++++++++++
>  mm/kmsan/hooks.c             | 11 +++++++++++
>  2 files changed, 25 insertions(+)
>
> diff --git a/include/linux/kmsan-checks.h b/include/linux/kmsan-checks.h
> index c4cae333deec..5218973f0ad0 100644
> --- a/include/linux/kmsan-checks.h
> +++ b/include/linux/kmsan-checks.h
> @@ -61,6 +61,17 @@ void kmsan_check_memory(const void *address, size_t si=
ze);
>  void kmsan_copy_to_user(void __user *to, const void *from, size_t to_cop=
y,
>                         size_t left);
>
> +/**
> + * kmsan_memmove_metadata() - Copy kernel memory range metadata.
> + * @dst: start of the destination kernel memory range.
> + * @src: start of the source kernel memory range.
> + * @n:   size of the memory ranges.
> + *
> + * KMSAN will treat the destination range as if its contents were memmov=
e()d
> + * from the source range.
> + */
> +void kmsan_memmove_metadata(void *dst, const void *src, size_t n);

As noted in patch 18/33, I am pretty sure we shouldn't need this function.