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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3C918CD68E3 for ; Tue, 10 Oct 2023 02:43:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1441926AbjJJCns (ORCPT ); Mon, 9 Oct 2023 22:43:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1441896AbjJJCnq (ORCPT ); Mon, 9 Oct 2023 22:43:46 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 041CBA6 for ; Mon, 9 Oct 2023 19:43:44 -0700 (PDT) Received: from dggpeml500002.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4S4Kqk3p83zkY09; Tue, 10 Oct 2023 10:39:46 +0800 (CST) Received: from [10.67.120.218] (10.67.120.218) by dggpeml500002.china.huawei.com (7.185.36.158) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Tue, 10 Oct 2023 10:43:42 +0800 Subject: Re: [PATCH] coresight: Fix crash when Perf and sysfs modes are used concurrently To: Suzuki K Poulose , James Clark , References: <20231006131452.646721-1-james.clark@arm.com> CC: Mike Leach , Alexander Shishkin , , From: hejunhao Message-ID: Date: Tue, 10 Oct 2023 10:43:42 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.120.218] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpeml500002.china.huawei.com (7.185.36.158) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/10/9 20:27, Suzuki K Poulose wrote: > Junhao He, > > Please could you test the patch and let us know if it resolves the > problem for you ? Hi James and Suzuki , I tested the patch on my platform and it worked well. > > On 06/10/2023 14:14, James Clark wrote: >> Partially revert the change in commit 6148652807ba ("coresight: Enable >> and disable helper devices adjacent to the path") which changed the bare >> call from source_ops(csdev)->enable() to coresight_enable_source() for >> Perf sessions. It was missed that coresight_enable_source() is >> specifically for the sysfs interface, rather than being a generic call. >> This interferes with the sysfs reference counting to cause the following >> crash: >> >> $ perf record -e cs_etm/@tmc_etr0/ -C 0 & >> $ echo 1 > /sys/bus/coresight/devices/tmc_etr0/enable_sink >> $ echo 1 > /sys/bus/coresight/devices/etm0/enable_source >> $ echo 0 > /sys/bus/coresight/devices/etm0/enable_source >> >> Unable to handle kernel NULL pointer dereference at virtual >> address 00000000000001d0 >> Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP >> ... >> Call trace: >> etm4_disable+0x54/0x150 [coresight_etm4x] >> coresight_disable_source+0x6c/0x98 [coresight] >> coresight_disable+0x74/0x1c0 [coresight] >> enable_source_store+0x88/0xa0 [coresight] >> dev_attr_store+0x20/0x40 >> sysfs_kf_write+0x4c/0x68 >> kernfs_fop_write_iter+0x120/0x1b8 >> vfs_write+0x2dc/0x3b0 >> ksys_write+0x70/0x108 >> __arm64_sys_write+0x24/0x38 >> invoke_syscall+0x50/0x128 >> el0_svc_common.constprop.0+0x104/0x130 >> do_el0_svc+0x40/0xb8 >> el0_svc+0x2c/0xb8 >> el0t_64_sync_handler+0xc0/0xc8 >> el0t_64_sync+0x1a4/0x1a8 >> Code: d53cd042 91002000 b9402a81 b8626800 (f940ead5) >> ---[ end trace 0000000000000000 ]--- >> >> This commit linked below also fixes the issue, but has unlocked updates >> to the mode which could potentially race. So until we come up with a >> more complete solution that takes all locking and interaction between >> both modes into account, just revert back to the old behavior for Perf. >> >> Reported-by: Junhao He >> Closes: >> https://lore.kernel.org/linux-arm-kernel/20230921132904.60996-1-hejunhao3@huawei.com/ >> Fixes: 6148652807ba ("coresight: Enable and disable helper devices >> adjacent to the path") >> Signed-off-by: James Clark > > The patch looks good to me. I will wait for Junhao to test this before > pulling it in. > > Suzuki > Tested-by: Junhao He Thanks. Junhao. > > > >> --- >> drivers/hwtracing/coresight/coresight-etm-perf.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c >> b/drivers/hwtracing/coresight/coresight-etm-perf.c >> index 5ca6278baff4..89e8ed214ea4 100644 >> --- a/drivers/hwtracing/coresight/coresight-etm-perf.c >> +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c >> @@ -493,7 +493,7 @@ static void etm_event_start(struct perf_event >> *event, int flags) >> goto fail_end_stop; >> /* Finally enable the tracer */ >> - if (coresight_enable_source(csdev, CS_MODE_PERF, event)) >> + if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF)) >> goto fail_disable_path; >> /* >> @@ -587,7 +587,7 @@ static void etm_event_stop(struct perf_event >> *event, int mode) >> return; >> /* stop tracer */ >> - coresight_disable_source(csdev, event); >> + source_ops(csdev)->disable(csdev, event); >> /* tell the core */ >> event->hw.state = PERF_HES_STOPPED; > > _______________________________________________ > CoreSight mailing list -- coresight@lists.linaro.org > To unsubscribe send an email to coresight-leave@lists.linaro.org > > . >