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Message-ID: <7c222eff6c1baaa7647a9aa43a1ef19de9670230.camel@linux.ibm.com>
Subject: Re: [PATCH 00/32] kmsan: Enable on s390
From:   Ilya Leoshkevich <iii@linux.ibm.com>
To:     Alexander Potapenko <glider@google.com>
Cc:     Alexander Gordeev <agordeev@linux.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.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>
Date:   Thu, 16 Nov 2023 11:13:39 +0100
In-Reply-To: <CAG_fn=U+X=EE9SSb61E=QDReBXn6PGiX4gJnMfNKsTwQ6saKcA@mail.gmail.com>
References: <20231115203401.2495875-1-iii@linux.ibm.com>
         <CAG_fn=U+X=EE9SSb61E=QDReBXn6PGiX4gJnMfNKsTwQ6saKcA@mail.gmail.com>
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On Thu, 2023-11-16 at 09:42 +0100, Alexander Potapenko wrote:
> On Wed, Nov 15, 2023 at 9:34=E2=80=AFPM Ilya Leoshkevich <iii@linux.ibm.c=
om>
> wrote:
> >=20
> > Hi,
> >=20
> > This series provides the minimal support for Kernel Memory
> > Sanitizer on
> > s390. Kernel Memory Sanitizer is clang-only instrumentation for
> > finding
> > accesses to uninitialized memory. The clang support for s390 has
> > already
> > been merged [1].
> >=20
> > With this series, I can successfully boot s390 defconfig and
> > debug_defconfig with kmsan.panic=3D1. The tool found one real
> > s390-specific bug (fixed in master).
> >=20
> > Best regards,
> > Ilya
>=20
> Hi Ilya,
>=20
> This is really impressive!
> Can you please share some instructions on how to run KMSAN in QEMU?
> I've never touched s390, but I'm assuming it should be possible?

I developed this natively (without cross-compilation or emulation,
just KVM), but I just gave the following a try on x86_64 and had some
success:

$ make LLVM=3D1 ARCH=3Ds390 O=3D../linux-build-s390x-cross CC=3Dclang-18
LD=3Ds390x-linux-gnu-ld OBJCOPY=3Ds390x-linux-gnu-objcopy debug_defconfig

$ make LLVM=3D1 ARCH=3Ds390 O=3D../linux-build-s390x-cross CC=3Dclang-18
LD=3Ds390x-linux-gnu-ld OBJCOPY=3Ds390x-linux-gnu-objcopy menuconfig

$ make LLVM=3D1 ARCH=3Ds390 O=3D../linux-build-s390x-cross CC=3Dclang-18
LD=3Ds390x-linux-gnu-ld OBJCOPY=3Ds390x-linux-gnu-objcopy -j24

$ qemu-system-s390x -M accel=3Dtcg -smp 2 -m 4G -kernel ../linux-build-
s390x-cross/arch/s390/boot/bzImage -nographic -append 'root=3D/dev/vda1
rw console=3DttyS1 nokaslr earlyprintk cio_ignore=3Dall kmsan.panic=3D1' -
object rng-random,filename=3D/dev/urandom,id=3Drng0 -device virtio-rng-
ccw,rng=3Drng0

It's also possible to get a free s390 machine at [1].

[1] https://linuxone.cloud.marist.edu/oss