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Mon, 08 Dec 2025 16:08:52 +0000 Received: from smtpav05.fra02v.mail.ibm.com (smtpav05.fra02v.mail.ibm.com [10.20.54.104]) by smtprelay03.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 5B8G8nEX55836948 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 8 Dec 2025 16:08:49 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2C60E20043; Mon, 8 Dec 2025 16:08:49 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3C4D220040; Mon, 8 Dec 2025 16:08:47 +0000 (GMT) Received: from [9.43.1.23] (unknown [9.43.1.23]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 8 Dec 2025 16:08:47 +0000 (GMT) Message-ID: <874f8ec4-4f3f-402d-a9f2-4267d37a5bc9@linux.ibm.com> Date: Mon, 8 Dec 2025 21:38:46 +0530 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/3] powerpc64/ftrace: workaround clang recording GEP in __patchable_function_entries To: Naveen N Rao Cc: linuxppc-dev , Madhavan Srinivasan , Christophe Leroy , Michael Ellerman , linux-trace-kernel@vger.kernel.org, Mark Rutland , Steven Rostedt , Masami Hiramatsu , llvm@lists.linux.dev, Maryam Moghadas References: <20251108210405.2375472-1-hbathini@linux.ibm.com> <20251108210405.2375472-4-hbathini@linux.ibm.com> Content-Language: en-US From: Hari Bathini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMjA2MDAyMCBTYWx0ZWRfX9VNsTMEkm0V3 acsg7v1LTpLHtW9U1nkuRwh/sSfQ49XoY6HPI2267UdlTK7KkOM1vN7aRVq9IzbGlxSDf7iFNgr VYgv/k7Mstt68u3/Xa2UlCWSyYER6IDKDxjItOVdT7MBzN0kfY7j7DGbWUEbSHuKUZw8cqMN4RM VPRqb+diMMxpw2/3aXXfQvA7+IFN+HAdnCVOETLOz3iMTZ32DCpoUc/yJHsFV831aE9WN0tBgA/ 3CL06XiUmzNVWu92c+MAzm1zgZuWnyY+RbPodBqI0NJUqHc2xHExyZJ2KRN0ahJN/eX8KIaO4h9 LJWQL3o4+7mOQM7tuy46q+MvJ883LTsrtzmr0A2W6W2+Ugw0a74+N5aqwKlId8ywLIS3hlaiZO0 VVD6jffw16hRmjvkomzbisHCbFlmRA== X-Authority-Analysis: v=2.4 cv=S/DUAYsP c=1 sm=1 tr=0 ts=6936f815 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=wP3pNCr1ah4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=cFmaXs7E2_rN6eu18uoA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: nQw_vPY9gvYZw9Fvk4z581Q2D8Yku0B- X-Proofpoint-GUID: nQw_vPY9gvYZw9Fvk4z581Q2D8Yku0B- X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-12-06_02,2025-12-04_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 phishscore=0 clxscore=1015 impostorscore=0 suspectscore=0 lowpriorityscore=0 adultscore=0 spamscore=0 bulkscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2512060020 On 24/11/25 11:25 am, Naveen N Rao wrote: > On Sun, Nov 09, 2025 at 02:34:05AM +0530, Hari Bathini wrote: >> Support for -fpatchable-function-entry on ppc64le was added in Clang >> with [1]. However, when no prefix NOPs are specified - as is the case >> with CONFIG_PPC_FTRACE_OUT_OF_LINE - the first NOP is emitted at LEP, >> but Clang records the Global Entry Point (GEP) unlike GCC which does >> record the Local Entry Point (LEP). Issue [2] has been raised to align >> Clang's behavior with GCC. As a temporary workaround to ensure ftrace > > Any reason to put in a "temporary" workaround rather than waiting for > this to be fixed? Pushing for this temporary workaround as the fix ETA for clang is not available at the moment and the temporary workaround is likely harmless even on a clang version with the fix included.. - Hari