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Thu, 31 Jul 2025 07:41:28 GMT Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 54E6E2004D; Thu, 31 Jul 2025 07:41:28 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 217BB2004B; Thu, 31 Jul 2025 07:41:28 +0000 (GMT) Received: from [9.152.212.130] (unknown [9.152.212.130]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 31 Jul 2025 07:41:28 +0000 (GMT) Message-ID: <82a66615-801a-40cd-a21c-ec82ff43b5d7@linux.ibm.com> Date: Thu, 31 Jul 2025 09:41:27 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf] libbpf: eBPF fails on events with auxiliary data To: Jiri Olsa , Ian Rogers , Ilya Leoshkevich Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-perf-users@vger.kernel.org, acme@kernel.org, namhyung@kernel.org, bpf@vger.kernel.org, agordeev@linux.ibm.com, gor@linux.ibm.com, sumanthk@linux.ibm.com, hca@linux.ibm.com, japo@linux.ibm.com References: <20250725093405.3629253-1-tmricht@linux.ibm.com> Content-Language: en-US From: Thomas Richter Organization: IBM In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNzMxMDA0OSBTYWx0ZWRfX4pYwqzUpWYvC 3wFg9hKJkh25Ixuv85vs3bzFXkmdloMN8zelvfLtCC/RuXspFGmhwZtfdIWcR3WcU9FekTy9NTS d/HLr3ZqfaydDIRBBIBUIh6VwDNbMzqdNLDUG/My6uzENq3wtE4iN9kDu0O+faTfWRPL62Ithk7 U748MVnLIoeD9GnHQkUvWik2DWfcwUGU+lfS9A+dIhP4wwNXMEH1KrU1jbWmtQfWyrBlXk6TzEV E2J3JK19aWYC+74GaqKD2IZPyCox6p9zHzTvm3TKSn4vev2b6WvxofV4Kn2S0pMT/fMPAE6fI07 5h/qU9mLgpbDtCLUtWnVMz+3DCHSAb6BlhUO/zIYz7pQpIn0J/KrTAewx7+U3docQmhpNzdtLtB jZwuDCRgdS2+lm0GNywhXXlOE4j7dUSHOhl524ySGRBdwyGqSnF7ANZsqDrgtMRbudP1Enj9 X-Authority-Analysis: v=2.4 cv=Je28rVKV c=1 sm=1 tr=0 ts=688b1e2e cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=Wb1JkmetP80A:10 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=RVNz8nRQakF0jqo7AOMA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: mwd1r9qpu6Ul4AoN6c2hLyfT0Wx9z5gX X-Proofpoint-ORIG-GUID: YFxsJRDDPRYkMghc81ie9jQW5cKEQGEA X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-07-31_01,2025-07-31_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 clxscore=1015 lowpriorityscore=0 spamscore=0 adultscore=0 suspectscore=0 bulkscore=0 malwarescore=0 priorityscore=1501 phishscore=0 mlxscore=0 impostorscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2507310049 On 7/25/25 16:06, Jiri Olsa wrote: > On Fri, Jul 25, 2025 at 11:34:05AM +0200, Thomas Richter wrote: >> On linux-next >> commit b4c658d4d63d61 ("perf target: Remove uid from target") >> introduces a regression on s390. In fact the regression exists >> on all platforms when the event supports auxiliary data gathering. >> >> Command >> # ./perf record -u 0 -aB --synth=no -- ./perf test -w thloop >> [ perf record: Woken up 1 times to write data ] >> [ perf record: Captured and wrote 0.011 MB perf.data ] >> # ./perf report --stats | grep SAMPLE >> # .... >> - goto err_out; >> - } > > I think this might break existing users depending on this > > could we instead add some 'enable' flag to bpf_perf_event_opts and perf > would use bpf_program__attach_perf_event_opts function instead? > > jirka > Hi Jiri, Ilya and Ian, Jiri recommended a more flexible approach and I submitted version 2 https://lore.kernel.org/all/20250728144340.711196-1-tmricht@linux.ibm.com This version now also passed the eBPF ci-test suite. I am blind on the eBPF topic and do not have enough knowledge to dig deeper into eBPF. Please note that this is not an s390 specific issue. It happens on other platforms when the event supports auxiliary data gathering, i. e. has_aux() returns true. I would like to ask someone with more eBPF knowledge for some help to drive this further. Thanks a lot. -- Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany -- IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Wolfgang Wendt Geschäftsführung: David Faller Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294