From patchwork Fri Oct 6 13:14:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Clark X-Patchwork-Id: 13411508 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 4AE96E81DF8 for ; Fri, 6 Oct 2023 13:16:19 +0000 (UTC) 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: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:In-Reply-To:References: List-Owner; bh=30US9PJ+upBaD4aMzF08guFX9rMsJSAgSi7oSClKDaA=; b=Y5UunvjZSBjnRq 0d6sbr4Pnk7vXvB6IoW7bY6PBr9P8sU3TnB5eHAwzgjfTYQF9i/dN93dEhvSeYNU+v8gDUrBu/oqm u9vnetStAm0E+IecS6R0/5nnSJm/+Zd3y15783E7N0IAtbwar0PBOp2seA9UCC8bsxkhJBnuzTGIG H5+pfJSLbr6IfiowtgiW/4vVn7sEvrxcnADHAt9byIkJjz1vpudapaTy4D//mzURFQe1IPzwzZENa DhzyulMVejP5F/shuduLujGQl9g1uHCkFMloR9WhG8rFHb7vkW2R9bCGlx2OVZl/4PeOvyNzZm8wO YIApiWjgLDEinFKg9cZg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qokgL-005rnU-0z; Fri, 06 Oct 2023 13:15:53 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qokgG-005rm1-0T for linux-arm-kernel@lists.infradead.org; Fri, 06 Oct 2023 13:15:51 +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 26F10C15; Fri, 6 Oct 2023 06:16:21 -0700 (PDT) Received: from localhost.localdomain (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 95A053F641; Fri, 6 Oct 2023 06:15:40 -0700 (PDT) From: James Clark To: coresight@lists.linaro.org, hejunhao3@huawei.com, suzuki.poulose@arm.com Cc: James Clark , Mike Leach , Leo Yan , Alexander Shishkin , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] coresight: Fix crash when Perf and sysfs modes are used concurrently Date: Fri, 6 Oct 2023 14:14:52 +0100 Message-Id: <20231006131452.646721-1-james.clark@arm.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231006_061548_252480_ADDFA37B X-CRM114-Status: GOOD ( 14.01 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 Tested-by: Junhao He --- 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;