From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49EFAC433E2 for ; Wed, 2 Sep 2020 15:29:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2CD1120767 for ; Wed, 2 Sep 2020 15:29:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726714AbgIBP3x (ORCPT ); Wed, 2 Sep 2020 11:29:53 -0400 Received: from foss.arm.com ([217.140.110.172]:40616 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728192AbgIBP3J (ORCPT ); Wed, 2 Sep 2020 11:29:09 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DD693101E; Wed, 2 Sep 2020 08:29:07 -0700 (PDT) Received: from ewhatever.cambridge.arm.com (ewhatever.cambridge.arm.com [10.1.197.1]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id DAFFF3F71F; Wed, 2 Sep 2020 08:29:06 -0700 (PDT) From: Suzuki K Poulose To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, mathieu.poirier@linaro.org, jeremy.linton@arm.com, coresight@lists.linaro.org, Suzuki K Poulose , Mike Leach Subject: [PATCH v2] coresight: etm4x: Handle unreachable sink in perf mode Date: Wed, 2 Sep 2020 16:28:47 +0100 Message-Id: <20200902152847.195909-1-suzuki.poulose@arm.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the specified/hinted sink is not reachable from a subset of the CPUs, we could end up unable to trace the event on those CPUs. This is the best effort we could do until we support 1:1 configurations. Fail gracefully in such cases avoiding a WARN_ON, which can be easily triggered by the user on certain platforms (Arm N1SDP), with the following trace paths : CPU0 \ -- Funnel0 --> ETF0 --> / \ CPU1 \ MainFunnel CPU2 / \ / -- Funnel1 --> ETF1 --> / CPU1 $ perf record --per-thread -e cs_etm/@ETF0/u -- could trigger the following WARNING, when the event is scheduled on CPU2. [10919.513250] ------------[ cut here ]------------ [10919.517861] WARNING: CPU: 2 PID: 24021 at drivers/hwtracing/coresight/coresight-etm-perf.c:316 etm_event_start+0xf8/0x100 ... [10919.564403] CPU: 2 PID: 24021 Comm: perf Not tainted 5.8.0+ #24 [10919.570308] pstate: 80400089 (Nzcv daIf +PAN -UAO BTYPE=--) [10919.575865] pc : etm_event_start+0xf8/0x100 [10919.580034] lr : etm_event_start+0x80/0x100 [10919.584202] sp : fffffe001932f940 [10919.587502] x29: fffffe001932f940 x28: fffffc834995f800 [10919.592799] x27: 0000000000000000 x26: fffffe0011f3ced0 [10919.598095] x25: fffffc837fce244c x24: fffffc837fce2448 [10919.603391] x23: 0000000000000002 x22: fffffc8353529c00 [10919.608688] x21: fffffc835bb31000 x20: 0000000000000000 [10919.613984] x19: fffffc837fcdcc70 x18: 0000000000000000 [10919.619281] x17: 0000000000000000 x16: 0000000000000000 [10919.624577] x15: 0000000000000000 x14: 00000000000009f8 [10919.629874] x13: 00000000000009f8 x12: 0000000000000018 [10919.635170] x11: 0000000000000000 x10: 0000000000000000 [10919.640467] x9 : fffffe00108cd168 x8 : 0000000000000000 [10919.645763] x7 : 0000000000000020 x6 : 0000000000000001 [10919.651059] x5 : 0000000000000002 x4 : 0000000000000001 [10919.656356] x3 : 0000000000000000 x2 : 0000000000000000 [10919.661652] x1 : fffffe836eb40000 x0 : 0000000000000000 [10919.666949] Call trace: [10919.669382] etm_event_start+0xf8/0x100 [10919.673203] etm_event_add+0x40/0x60 [10919.676765] event_sched_in.isra.134+0xcc/0x210 [10919.681281] merge_sched_in+0xb0/0x2a8 [10919.685017] visit_groups_merge.constprop.140+0x15c/0x4b8 [10919.690400] ctx_sched_in+0x15c/0x170 [10919.694048] perf_event_sched_in+0x6c/0xa0 [10919.698130] ctx_resched+0x60/0xa0 [10919.701517] perf_event_exec+0x288/0x2f0 [10919.705425] begin_new_exec+0x4c8/0xf58 [10919.709247] load_elf_binary+0x66c/0xf30 [10919.713155] exec_binprm+0x15c/0x450 [10919.716716] __do_execve_file+0x508/0x748 [10919.720711] __arm64_sys_execve+0x40/0x50 [10919.724707] do_el0_svc+0xf4/0x1b8 [10919.728095] el0_sync_handler+0xf8/0x124 [10919.732003] el0_sync+0x140/0x180 Even though we don't support using separate sinks for the ETMs yet (e.g, for 1:1 configurations), we should at least honor the user's choice and handle the limitations gracefully, by simply skipping the tracing on ETMs which can't reach the requested sink. Fixes: f9d81a657bb8 ("coresight: perf: Allow tracing on hotplugged CPUs") Reported-by: Jeremy Linton Tested-by: Jeremy Linton Cc: Mathieu Poirier Cc: Mike Leach Signed-off-by: Suzuki K Poulose --- Change since v1: - Updated the description, added Tested-by. - No code changes - Rebased on coresight/next --- drivers/hwtracing/coresight/coresight-etm-perf.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index 1a3169e69bb1..9d61a71da96f 100644 --- a/drivers/hwtracing/coresight/coresight-etm-perf.c +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c @@ -321,6 +321,16 @@ static void etm_event_start(struct perf_event *event, int flags) if (!event_data) goto fail; + /* + * Check if this ETM is allowed to trace, as decided + * at etm_setup_aux(). This could be due to an unreachable + * sink from this ETM. We can't do much in this case if + * the sink was specified or hinted to the driver. For + * now, simply don't record anything on this ETM. + */ + if (!cpumask_test_cpu(cpu, &event_data->mask)) + goto fail_end_stop; + path = etm_event_cpu_path(event_data, cpu); /* We need a sink, no need to continue without one */ sink = coresight_get_sink(path); -- 2.24.1