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Tue, 16 Sep 2025 13:48:03 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 883022004E; Tue, 16 Sep 2025 13:48:03 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4D36920040; Tue, 16 Sep 2025 13:48:03 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 16 Sep 2025 13:48:03 +0000 (GMT) From: Heiko Carstens To: Nathan Chancellor , Miguel Ojeda , Kees Cook , Nick Desaulniers , Vasily Gorbik , Alexander Gordeev , Juergen Christ Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Sven Schnelle , Christian Borntraeger Subject: [PATCH v2 0/4] s390: Fix and optimize __flogr() inline assembly Date: Tue, 16 Sep 2025 15:47:59 +0200 Message-ID: <20250916134803.874580-1-hca@linux.ibm.com> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=BKWzrEQG c=1 sm=1 tr=0 ts=68c96a98 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=yJojWOMRYYMA:10 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=JPAbe6LxEtc0jUXev0wA:9 X-Proofpoint-GUID: gYCdbgO0aHIEEAPfUaXuqFkUGh-iXkB4 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwOTE1MDA4NiBTYWx0ZWRfXz3Z7A178VOHN ep1Sov813ega64aFgMe6IYhhgTtsp5Xdx2UyPeZ86kBNLwMA05PMkIrra72jq8hCgP78WzuHNRY 62tMwaigk9nij1s0UWxDmqBpTbL77ApNjGbephBMffJf7OIJS6sEjEqvAWKGixUxXr2Qo9U15A0 H5A/oNbr427M8PshyUY61Qv9WYfcigbzWDYFt0S6n0mStXU19Ek/19qmpwo7Oy4QHzUhd3G9K93 xXlLQiISRPoe8IYvzdSolswC2fqrS591/QpRoysFCI/5m4Vy1Rzvf9xB8NjI0QdFVza6MRY+48c MMOQ9HTOT6s8HARH6ox8xXDbrrJL4PZWovfB/lEZiAUGF8ExNAfW5TKowNsJfGDJgRnliWW+ZwF oL2Bynjw X-Proofpoint-ORIG-GUID: yY1hrQJ8tkwJV8Fs2X0KtHI9herUS2_T X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-16_02,2025-09-12_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 clxscore=1015 malwarescore=0 priorityscore=1501 adultscore=0 suspectscore=0 impostorscore=0 bulkscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2509150086 v2: - Split patches differently, so that the first patch is the actual fix, which addresses the reported warning / error. The subsequent patches are optimizations v1: https://lore.kernel.org/all/20250910151216.646600-1-hca@linux.ibm.com/ A recent optimization of the s390 specific ffs() and ffs64() implementations leads to a new compiler warning. Instead of reverting the optimization address this with the rather new assume attribute, which generates even better code, if supported by compilers. Since the assume attribute may be useful for others as well, add the __assume macro to compiler attributes, so it is kernel wide available, instead of adding an s390 specific optimization. Heiko Carstens (4): s390/bitops: Limit return value range of __flogr() compiler_types: Add __assume macro s390/bitops: Use __assume() for __flogr() inline assembly return value s390/bitops: Cleanup __flogr() arch/s390/include/asm/bitops.h | 21 ++++++++++++++------- include/linux/compiler_types.h | 23 +++++++++++++++++++++++ init/Kconfig | 10 ++++++++++ 3 files changed, 47 insertions(+), 7 deletions(-) -- 2.48.1