From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3AC0317A305; Wed, 10 Jun 2026 00:51:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781052687; cv=none; b=VeLPNFEOPQqXcXmQR9eHftovLc2AcfmEtM4TBNCzh+fOfU65A4fKSw4QnHJoB9Ux+tqMONzSV1yOklIAE9TNTfl9HKUojOB3oWJPDGOxdNONkV7KO4RBbETRmEtOChY/T76WhNOroXDPVtbRWT4eshTEWdc7vUX+kEWUcR5mqE0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781052687; c=relaxed/simple; bh=hHSweqaoPPOWP//CiRXcgp6ysK37O1r6QEAl6tA6cSU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=gddaDY3ePmUwINdZILnNKwuGuvuH2PUF4IIWLPB5gWn3wuN9k+MMW6ZjXlwDVbBXCnsyHOAWJpfumwJr7v9RIuASufb235lYx4v9fmkuAryp5RRrc9+uHLKMqR/yNHa30llxhaB28MsMQQaIKliOGkjYy0NB/BvvEVVFaCL3KYk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Kh29NEbW; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Kh29NEbW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B14041F00893; Wed, 10 Jun 2026 00:51:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781052685; bh=AknOC9ftrQ9npWsX4G287ronaobFlPP7dg7D/271fCg=; h=From:To:Cc:Subject:Date; b=Kh29NEbWMMf5Dwxam8iyR8o0632/X5Fn4bfelwOtb9BkK11MH65DqlmD0pqOmMqmF PZSo+WesGN+gUdNj6PQ5kwR347apZtnzxRJqiDChzymX97AIfxbbdsKVAkV6tjFUts eccMq3EBPzzvaiLzw1GWYOpA1Qxopto93ZvaUoEb7rgQ9WIeCT44heH9pxv88JuLFF lBUcFJudrS3jIJp1gll1aVlEDwESrUhRQic2HW5hFghoC7zZFihXboBIvlHu3tq9S0 uUvXdQm8NaMjWpEV1rFEmx0cZLfOxK97OEwzN60rHaZ0tkbAMyPilMdpJ/2kONOSyw jHbusxyGvOtaw== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Mathieu Desnoyers Cc: Jonathan Corbet , Shuah Khan , Masami Hiramatsu , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [RFC PATCH v2 0/7] tracing/probes: Add more typecast features Date: Wed, 10 Jun 2026 09:51:21 +0900 Message-ID: <178105268094.21760.13668249930524377840.stgit@devnote2> X-Mailer: git-send-email 2.43.0 User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Hi, Here is the 2nd version of series to introduce more typecast features to probe events. The previous version is here: https://lore.kernel.org/all/178092865666.163648.10457567771536160909.stgit@devnote2/ In this version, I fixed various problems Sashiko reviewed and add a fix of sample code. Also drop +CPU/PCPU() and introduce this_cpu_read(). Steve introduced BTF typecast feature for eprobe[1]. This series extends it and add more options: 1. Expanding BTF typecast to kprobe and fprobe. (currently only function entry/exit) 2. Introduce container_of like typecast. This adds a "assigned member" option to the typecast. (STRUCT,MEMBER)VAR->ANOTHER_MEMBER This casts VAR to STRUCT type but the VAR is as the address of STRUCT.MEMBER. In C, it is: container_of(VAR, STRUCT, MEMBER)->ANOTHER_MEMBER 3. Support nested typecast, e.g. (STRUCT)((STRUCT2)VAR->MEMBER2)->MEMBER the nest level must be smaller than 3. 4. Add $current variable to point "current" task_struct. This is useful with typecast, e.g. (task_struct)$current->pid 5. per-cpu dereference support. Intrdouce this_cpu_read(VAR) and this_cpu_ptr(VAR) to access per-cpu data on the current CPU (accessing other CPU data is not stable, because it can be changed.) You can access the member of per-cpu data structure using typecast like: (STRUCT)this_cpu_ptr(VAR)->MEMBER And added a test script to test part of them. [1] https://lore.kernel.org/all/20260601130746.2139d926@gandalf.local.home/ --- Masami Hiramatsu (Google) (7): tracing/events: Fix to check the simple_tsk_fn creation tracing/probes: Support typecast for various probe events tracing/probes: Support nested typecast tracing/probes: Support field specifier option for typecast tracing/probes: Add $current variable support tracing/probes: Add this_cpu_read() and this_cpu_ptr() dereference method to fetcharg tracing/probes: Add a new testcase for BTF typecasts Documentation/trace/eprobetrace.rst | 10 Documentation/trace/fprobetrace.rst | 10 Documentation/trace/kprobetrace.rst | 11 + kernel/trace/trace.c | 6 kernel/trace/trace_probe.c | 404 +++++++++++++++----- kernel/trace/trace_probe.h | 18 + kernel/trace/trace_probe_tmpl.h | 33 +- samples/trace_events/trace-events-sample.c | 56 ++- samples/trace_events/trace-events-sample.h | 34 ++ .../ftrace/test.d/dynevent/btf_probe_event.tc | 51 +++ 10 files changed, 509 insertions(+), 124 deletions(-) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/btf_probe_event.tc -- Masami Hiramatsu (Google)