Re: [PATCH v2 09/33] kmsan: Introduce kmsan_memmove_metadata()

[Alexander Potapenko]

On Tue, Nov 21, 2023 at 11:07 PM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
> ---
>  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 size);
>  void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy,
>                         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 memmove()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.