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charset="us-ascii" Content-ID: <22E648044058D844ADB93EB37E311ECC@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 7be8c581-a0c3-4204-3870-08d6da597a6c X-MS-Exchange-CrossTenant-originalarrivaltime: 16 May 2019 23:51:55.8579 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR15MB1150 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-16_19:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905160144 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi,=20 We found a failure with selftests/bpf/tests_prog in test_stacktrace_map (on= bpf/master branch).=20 After digging into the code, we found that perf_callchain_kernel() is givin= g empty callchain for tracepoint sched/sched_switch. And it seems related to commit d15d356887e770c5f2dcf963b52c7cb510c9e42d ("perf/x86: Make perf callchains work without CONFIG_FRAME_POINTER") Before this commit, perf_callchain_kernel() returns callchain with regs->ip= . With this commit, regs->ip is not sent for !perf_hw_regs(regs) case.=20 I found the following change fixes the selftest. But I am not very sure, it= is=20 the best solution here.=20 Please share comments and suggestions on this.=20 Thanks in advance! Song diff --git i/arch/x86/events/core.c w/arch/x86/events/core.c index f315425d8468..7b8a9eb4d5fd 100644 --- i/arch/x86/events/core.c +++ w/arch/x86/events/core.c @@ -2402,9 +2402,9 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx= *entry, struct pt_regs *re return; } + if (perf_callchain_store(entry, regs->ip)) + return; if (perf_hw_regs(regs)) { - if (perf_callchain_store(entry, regs->ip)) - return; unwind_start(&state, current, regs, NULL); } else { unwind_start(&state, current, NULL, (void *)regs->sp);