From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3yp2Kw274szDsF5 for ; Fri, 1 Dec 2017 16:06:11 +1100 (AEDT) Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vB155p4K040543 for ; Fri, 1 Dec 2017 00:06:05 -0500 Received: from e06smtp12.uk.ibm.com (e06smtp12.uk.ibm.com [195.75.94.108]) by mx0a-001b2d01.pphosted.com with ESMTP id 2ek0cdgtrj-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 01 Dec 2017 00:06:05 -0500 Received: from localhost by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 1 Dec 2017 05:06:02 -0000 Subject: Re: [PATCH] powerpc/perf: Fix oops when grouping different pmu events To: Ravi Bangoria , mpe@ellerman.id.au Cc: benh@kernel.crashing.org, paulus@samba.org, tglx@linutronix.de, kan.liang@intel.com, sukadev@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <20171130083322.31206-1-ravi.bangoria@linux.vnet.ibm.com> From: Madhavan Srinivasan Date: Fri, 1 Dec 2017 10:35:56 +0530 MIME-Version: 1.0 In-Reply-To: <20171130083322.31206-1-ravi.bangoria@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Message-Id: List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thursday 30 November 2017 02:03 PM, Ravi Bangoria wrote: > When user tries to group imc (In-Memory Collections) event with > normal event, (sometime) kernel crashes with following log: > > Faulting instruction address: 0x00000000 > [link register ] c00000000010ce88 power_check_constraints+0x128/0x980 > ... > c00000000010e238 power_pmu_event_init+0x268/0x6f0 > c0000000002dc60c perf_try_init_event+0xdc/0x1a0 > c0000000002dce88 perf_event_alloc+0x7b8/0xac0 > c0000000002e92e0 SyS_perf_event_open+0x530/0xda0 > c00000000000b004 system_call+0x38/0xe0 > > 'event_base' field of 'struct hw_perf_event' is used as flags for > normal hw events and used as memory address for imc events. While > grouping these two types of events, collect_events() tries to > interpret imc 'event_base' as a flag, which causes a corruption > resulting in a crash. > > Consider only those events which belongs to 'perf_hw_context' in > collect_events(). Reviewed-By: Madhavan Srinivasan > > Signed-off-by: Ravi Bangoria > --- > arch/powerpc/perf/core-book3s.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c > index 9e3da16..1538129 100644 > --- a/arch/powerpc/perf/core-book3s.c > +++ b/arch/powerpc/perf/core-book3s.c > @@ -1415,7 +1415,7 @@ static int collect_events(struct perf_event *group, int max_count, > int n = 0; > struct perf_event *event; > > - if (!is_software_event(group)) { > + if (group->pmu->task_ctx_nr == perf_hw_context) { > if (n >= max_count) > return -1; > ctrs[n] = group; > @@ -1423,7 +1423,7 @@ static int collect_events(struct perf_event *group, int max_count, > events[n++] = group->hw.config; > } > list_for_each_entry(event, &group->sibling_list, group_entry) { > - if (!is_software_event(event) && > + if (event->pmu->task_ctx_nr == perf_hw_context && > event->state != PERF_EVENT_STATE_OFF) { > if (n >= max_count) > return -1;