From: Heiko Carstens <hca@linux.ibm.com>
To: Aleksei Nikiforov <aleksei.nikiforov@linux.ibm.com>
Cc: Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Thomas Huth <thuth@redhat.com>,
Juergen Christ <jchrist@linux.ibm.com>,
Ilya Leoshkevich <iii@linux.ibm.com>
Subject: Re: [PATCH v2] s390/fpu: Fix false-positive kmsan report in fpu_vstl function
Date: Mon, 10 Nov 2025 10:30:17 +0100 [thread overview]
Message-ID: <20251110093017.15528A26-hca@linux.ibm.com> (raw)
In-Reply-To: <20251107155914.1407772-3-aleksei.nikiforov@linux.ibm.com>
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@linux.ibm.com>
> ---
> arch/s390/include/asm/fpu-insn.h | 3 +++
> 1 file changed, 3 insertions(+)
Applied, thanks!
prev parent reply other threads:[~2025-11-10 9:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-07 15:59 [PATCH v2] s390/fpu: Fix false-positive kmsan report in fpu_vstl function Aleksei Nikiforov
2025-11-10 9:30 ` Heiko Carstens [this message]
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