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Mon, 24 Mar 2025 10:47:05 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 694862004B; Mon, 24 Mar 2025 10:47:05 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CD8DB20040; Mon, 24 Mar 2025 10:47:03 +0000 (GMT) Received: from osiris (unknown [9.179.14.66]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTPS; Mon, 24 Mar 2025 10:47:03 +0000 (GMT) Date: Mon, 24 Mar 2025 11:47:02 +0100 From: Heiko Carstens To: Alessandro Carminati Cc: Guenter Roeck , linux-kselftest@vger.kernel.org, David Airlie , Arnd Bergmann , =?iso-8859-1?Q?Ma=EDra?= Canal , Dan Carpenter , Kees Cook , Daniel Diaz , David Gow , Arthur Grillo , Brendan Higgins , Naresh Kamboju , Maarten Lankhorst , Andrew Morton , Maxime Ripard , Ville =?iso-8859-1?Q?Syrj=E4l=E4?= , Daniel Vetter , Thomas Zimmermann , Alessandro Carminati , Jani Nikula , dri-devel@lists.freedesktop.org, kunit-dev@googlegroups.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, loongarch@lists.linux.dev, x86@kernel.org, Linux Kernel Functional Testing , Vasily Gorbik , Alexander Gordeev Subject: Re: [PATCH v4 10/14] s390: Add support for suppressing warning backtraces Message-ID: <20250324104702.12139E73-hca@linux.ibm.com> References: <20250313114329.284104-1-acarmina@redhat.com> <20250313114329.284104-11-acarmina@redhat.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-GUID: -BXK6qMXWLef6jiJ2R9hHCsaI_IjDOmx X-Proofpoint-ORIG-GUID: 40o9NRITvQhnDK-iPsw_sUFfSwFPyp4T X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1093,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-24_04,2025-03-21_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 suspectscore=0 priorityscore=1501 impostorscore=0 spamscore=0 adultscore=0 mlxscore=0 mlxlogscore=810 clxscore=1011 malwarescore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2503240076 On Fri, Mar 21, 2025 at 10:05:42PM +0100, Alessandro Carminati wrote: > > > +#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE > > > +# define HAVE_BUG_FUNCTION > > > +# define __BUG_FUNC_PTR " .long %0-.\n" > > > +# define __BUG_FUNC __func__ > > > > gcc 7.5.0 on s390 barfs; it doesn't like the use of "__func__" with "%0-." ... > GCC makes significant efforts to handle this, and for several > architectures, it manages to solve the problem. > However, this is not universally the case. > Additionally, -fPIC is not widely used in kernel code... I have only > seen it used for VDSO, the x86 boot piggyback decompressor, PowerPC > boot, and the s390x architecture. > > That said, GCC has been mitigating this issue, allowing us to treat a > non-compile-time constant as if it were one. > A proof of this is that, at least since GCC 11, the s390x version of > GCC is able to build this code. > Before that... certainly in GCC 7.5 it couldn't. > > A simple fix would be to restrict usage to GCC versions greater than > 11 for s390. But please add that dependency only for this new feature for the time being. Right now I would not like to see that s390 is the only architecture (besides parisc) which requires a much higher minimum gcc level than every other architecture. Unless there are specific reasons.