Re: [PATCH v2] s390/fpu: Fix false-positive kmsan report in fpu_vstl function

[Heiko Carstens]

On Fri, Nov 07, 2025 at 04:59:16PM +0100, Aleksei Nikiforov wrote:
> A false-positive kmsan report is detected when running ping command.
> 
> An inline assembly instruction 'vstl' can write varied amount of bytes
> depending on value of 'index' argument. If 'index' > 0, 'vstl' writes
> at least 2 bytes.
> 
> clang generates kmsan write helper call depending on inline assembly
> constraints. Constraints are evaluated compile-time, but value of
> 'index' argument is known only at runtime.
> 
> clang currently generates call to __msan_instrument_asm_store with 1 byte
> as size. Manually call kmsan function to indicate correct amount of bytes
> written and fix false-positive report.
...
> Fixes: dcd3e1de9d17 ("s390/checksum: provide csum_partial_copy_nocheck()")
> Signed-off-by: Aleksei Nikiforov <aleksei.nikiforov@xxxxxxxxxxxxx>
> ---
>  arch/s390/include/asm/fpu-insn.h | 3 +++
>  1 file changed, 3 insertions(+)

Applied, thanks!