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Mon, 26 Oct 2026 12:03:30 +0000 (GMT) Received: from tuxmaker.lnxne.boe (unknown [9.87.85.9]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 26 Oct 2026 12:03:30 +0000 (GMT) From: Heiko Carstens To: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Ilya Leoshkevich Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: [PATCH 1/4] s390/jump_label: Serialize text patching with text_mutex Date: Mon, 26 Oct 2026 13:03:26 +0100 Message-ID: <20261026120329.1792436-2-hca@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261026120329.1792436-1-hca@linux.ibm.com> References: <20261026120329.1792436-1-hca@linux.ibm.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDI2MDA0NiBTYWx0ZWRfX8vXI1n/2007y WVexTP0Hj+fIg/vj3LZlLHI7g+Db1CJ/0p9RWaVr6jrndL9IkGAZUXhk/8b3gEnbcNTrfEg5ChY ZAbey86AN3SrDwx1Do6LLEW9w5TmoGs= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDI2MDA0NiBTYWx0ZWRfXwLB1zcEch5zL DkTPvfw404/mwwUf8BTuCT6xdZB8CN1to9TTrOSIGJkh2ZVN0MHvaKuBOEGt78oGib/zOFrsrAq KF+4BV+xPHfFa4a0DZRyvn3mznHVqCzyAzcgXneOV/XpWvYnhnXEdGrNV0whaKbkYC9nj1Ydf3c poLB9u7Jl2r8sQb7NQNzvt54cgnWtam4Kr/B2AqkAIA40b3v/1N+p9YR6CIIwqs/PKasP+D/bFR kv5fR6cD+bLOptkD+rP/MeF3xeV4H1oOY1rO3LW86stfV9c5LjFL2DWnrVeilp4nGbbPq5UoFa5 FP+CDc9tTCUC1uwf5POKZsgMoQmxq01s8j7Be4FWyPTNQyyM7AXTivs3BkTUeJbApuqpLVZfO1n aU0IhV3ZxiakdWUYXwcnRHlryC/PfOYJ4J9uUNdQq1+pvWvmYRK2Qh+6kAP+gB/RtKVXVTjJCOY HaUX6M7Dp4UXIgvfcxA== X-Proofpoint-ORIG-GUID: PV_DNF0FDcSiaNC5W6deopK-GwcE09VD X-Authority-Analysis: v=2.4 cv=Uu32pOwB c=1 sm=1 tr=0 ts=6adf4197 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=Qv2Z5fm34N4ByW7sTngA:9 X-Proofpoint-GUID: PV_DNF0FDcSiaNC5W6deopK-GwcE09VD X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-10-26_02,2026-10-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 impostorscore=0 priorityscore=1501 spamscore=0 adultscore=0 lowpriorityscore=0 malwarescore=0 clxscore=1015 suspectscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610190000 definitions=main-2610260046 Acquire text_mutex around the verify-then-patch sequence in jump_label_transform(). This way s390 uses text_mutex like other architectures and does not need to rely on other implicit semantics (e.g. no kprobe can be set on a jump label). This is a prereq for removing the spinlock in __s390_kernel_write(). Signed-off-by: Heiko Carstens --- arch/s390/kernel/jump_label.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/s390/kernel/jump_label.c b/arch/s390/kernel/jump_label.c index e808bb8bc0da..682069673f48 100644 --- a/arch/s390/kernel/jump_label.c +++ b/arch/s390/kernel/jump_label.c @@ -5,6 +5,7 @@ * Copyright IBM Corp. 2011 * Author(s): Jan Glauber */ +#include #include #include #include @@ -57,9 +58,11 @@ static void jump_label_transform(struct jump_entry *entry, jump_label_make_branch(entry, &old); jump_label_make_nop(entry, &new); } + mutex_lock(&text_mutex); if (memcmp(code, &old, sizeof(old))) jump_label_bug(entry, &old, &new); s390_kernel_write(code, &new, sizeof(new)); + mutex_unlock(&text_mutex); } void arch_jump_label_transform(struct jump_entry *entry, -- 2.53.0