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=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 C893BC433EF for ; Thu, 23 Sep 2021 14:43:12 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9C66D610D1 for ; Thu, 23 Sep 2021 14:43:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 9C66D610D1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=EOD6APFZ5CWAp79iJQYTcZmmray/t70lCGjbZTE3gUs=; b=2zZtem8nEYfGPA hKndlWEPaosjV0SSo4rLA/hLlZfGxyB522nfsUIqR37VWnN3dnAE1bU0Ik/5TJQc09AYWaTi2LJN1 uHSBZBIYo6w99TT+iStwKYqbJQNexRvTYKZedticWBZen3XmqF5vue5EMEdm0B/iIEucESLq1e4jw 9+F+BG6AdOJZ46gxMX6cb9ZpwoaOzimmqbJYs1Qq38EoT+2VpUlrT6zIcPpw7JuWdFYjvG38a/pIl KPcggcC9UwemzF4Y7iXeHnkEIDqI+YxtrhroIuljK6ciiV8mK7TibdcRWsB0yvocBkOf8iua8JgD5 lYqGEZC2D0zpFKSNGA5w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mTPtQ-00BrEz-Si; Thu, 23 Sep 2021 14:40:08 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mTPst-00Br7S-F2 for linux-arm-kernel@lists.infradead.org; Thu, 23 Sep 2021 14:39:37 +0000 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 E94C812FC; Thu, 23 Sep 2021 07:39:34 -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 B40773F718; Thu, 23 Sep 2021 07:39:33 -0700 (PDT) From: Suzuki K Poulose To: mathieu.poirier@linaro.org, linux-arm-kernel@lists.infradead.org Cc: anshuman.khandual@arm.com, mike.leach@linaro.org, leo.yan@linaro.org, coresight@lists.linaro.org, linux-kernel@vger.kernel.org, Suzuki K Poulose , James Clark Subject: [PATCH v4 3/5] coresight: trbe: Do not truncate buffer on IRQ Date: Thu, 23 Sep 2021 15:39:17 +0100 Message-Id: <20210923143919.2944311-4-suzuki.poulose@arm.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20210923143919.2944311-1-suzuki.poulose@arm.com> References: <20210923143919.2944311-1-suzuki.poulose@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210923_073935_637722_6740A70F X-CRM114-Status: GOOD ( 20.34 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The TRBE driver marks the AUX buffer as TRUNCATED when we get an IRQ on FILL event. This has rather unwanted side-effect of the event being disabled when there may be more space in the ring buffer. So, instead of TRUNCATE we need a different flag to indicate that the trace may have lost a few bytes (i.e from the point of generating the FILL event until the IRQ is consumed). Anyways, the userspace must use the size from RECORD_AUX headers to restrict the "trace" decoding. Using PARTIAL flag causes the perf tool to generate the following warning: Warning: AUX data had gaps in it XX times out of YY! Are you running a KVM guest in the background? which is pointlessly scary for a user. The other remaining options are : - COLLISION - Use by SPE to indicate samples collided - Add a new flag - Specifically for CoreSight, doesn't sound so good, if we can re-use something. Given that we don't already use the "COLLISION" flag, the above behavior can be notified using this flag for CoreSight. Cc: Mathieu Poirier Cc: James Clark Cc: Mike Leach Cc: Anshuman Khandual Cc: Leo Yan Signed-off-by: Suzuki K Poulose --- Changes since v3: - Moved setting the COLLISION flag to a helper and added comments to explain. --- drivers/hwtracing/coresight/coresight-trbe.c | 27 +++++++++++++++----- 1 file changed, 21 insertions(+), 6 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index 47120d263639..0a9106c15639 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -120,6 +120,25 @@ static void trbe_reset_local(void) write_sysreg_s(0, SYS_TRBSR_EL1); } +static void trbe_report_wrap_event(struct perf_output_handle *handle) +{ + /* + * Mark the buffer to indicate that there was a WRAP event by + * setting the COLLISION flag. This indicates to the user that + * the TRBE trace collection was stopped without stopping the + * ETE and thus there might be some amount of trace that was + * lost between the time the WRAP was detected and the IRQ + * was consumed by the CPU. + * + * Setting the TRUNCATED flag would move the event to STOPPED + * state unnecessarily, even when there is space left in the + * ring buffer. Using the COLLISION flag doesn't have this side + * effect. We only set TRUNCATED flag when there is no space + * left in the ring buffer. + */ + perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION); +} + static void trbe_stop_and_truncate_event(struct perf_output_handle *handle) { struct trbe_buf *buf = etm_perf_sink_config(handle); @@ -612,7 +631,7 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev, * for correct size. Also, mark the buffer truncated. */ write = get_trbe_limit_pointer(); - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); + trbe_report_wrap_event(handle); } offset = write - base; @@ -708,11 +727,7 @@ static void trbe_handle_overflow(struct perf_output_handle *handle) if (buf->snapshot) handle->head += size; - /* - * Mark the buffer as truncated, as we have stopped the trace - * collection upon the WRAP event, without stopping the source. - */ - perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED); + trbe_report_wrap_event(handle); perf_aux_output_end(handle, size); event_data = perf_aux_output_begin(handle, event); if (!event_data) { -- 2.24.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel