From patchwork Fri Sep 1 20:43:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Beau Belgrave X-Patchwork-Id: 13372893 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 B8008CA0FF9 for ; Fri, 1 Sep 2023 20:43:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350745AbjIAUnm (ORCPT ); Fri, 1 Sep 2023 16:43:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55976 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245611AbjIAUnm (ORCPT ); Fri, 1 Sep 2023 16:43:42 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E84F0E7F; Fri, 1 Sep 2023 13:43:38 -0700 (PDT) Received: from localhost.localdomain (unknown [4.155.48.116]) by linux.microsoft.com (Postfix) with ESMTPSA id 5FDA9212A77F; Fri, 1 Sep 2023 13:43:38 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 5FDA9212A77F DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1693601018; bh=Hf9SnXuceZoq/4/ofWf9A3vljxlLROGDFUiObueCNRA=; h=From:To:Cc:Subject:Date:From; b=fbpcM+2borID5F7aXvRUS8dbyap3lmwghhlvbZ4vyke2NDcgKfG6I11aazX3+MnBN /3gCurGAPs36iohHOK7EPXKH0OArug9ZrgbJlUH9TXa3v9Nt664JU7h/r/iJ2zT4L7 SSTbzQYvlJwGZboztLfZ+oG2xh7Rca1voJl9jN8w= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, ast@kernel.org, dcook@linux.microsoft.com Subject: [PATCH 0/3] tracing/user_events: Allow events to persist for perfmon_capable users Date: Fri, 1 Sep 2023 20:43:29 +0000 Message-Id: <20230901204332.159-1-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org There are several scenarios that have come up where having a user_event persist even if the process that registered it exits. The main one is having a daemon create events on bootup that shouldn't get deleted if the daemon has to exit or reload. Another is within OpenTelemetry exporters, they wish to potentially check if a user_event exists on the system to determine if exporting the data out should occur. The user_event in this case must exist even in the absence of the owning process running (such as the above daemon case). Since persistent events aren't automatically cleaned up, we want to ensure only trusted users are allowed to do this. It seems reasonable to use CAP_PERFMON as that boundary, since those users can already do many things via perf_event_open without requiring full CAP_SYS_ADMIN. This patchset brings back the ability to use /sys/kernel/tracing/dynamic_events to create user_events, as persist is now back to being supported. Both the register and delete of events that persist require CAP_PERFMON, which prevents a non-perfmon user from making an event go away that a perfmon user decided should persist. Beau Belgrave (3): tracing/user_events: Allow events to persist for perfmon_capable users selftests/user_events: Test persist flag cases tracing/user_events: Document persist event flags Documentation/trace/user_events.rst | 21 ++++++- include/uapi/linux/user_events.h | 11 +++- kernel/trace/trace_events_user.c | 28 +++++----- .../testing/selftests/user_events/abi_test.c | 55 ++++++++++++++++++- .../testing/selftests/user_events/dyn_test.c | 54 +++++++++++++++++- 5 files changed, 149 insertions(+), 20 deletions(-) base-commit: f940e482b0f889e697372a22b6c15da87aa1f63a