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 3D9CB3CA486; Wed, 24 Jun 2026 14:41:31 +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=1782312093; cv=none; b=kY6oB9rOTpXu4KtkwVMPq5pnIAWFiKnnEL9bF6tD9E0BsdljjrK8gAjjkosfh+Zqm7dlxne+fDXF+/0Zm7eRyOYcLvQ8YeAx7PgJDYOR45bw4/7fDYq/NUUw2pmCoYzVbbsQDza9zONGoBr/09n+JSq30KDzaSwvChRkQYMvDog= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782312093; c=relaxed/simple; bh=rVG0zrvhoLLqupHeedRrLHQngjssH75ENT3IpSBjtLg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=Q3LM4mCGG2odz/kIr9BOO3dtjcfyU/Kr/zJuMiOFd2agb/9e2MQcvKqhLHpOqIPgdEe3UzYBhUnJvzNv6Oi+idraBAefm9XRaipNHQQbB39aqLyQWjXIGk83OFAKj+OQOEwsSHrtLHYt+xgKRw2rlUlW/HamL02K6EhxxzE88Mc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OnyFrDSV; 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="OnyFrDSV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE3CA1F000E9; Wed, 24 Jun 2026 14:41:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782312091; bh=LYDX4vbUgsadUQdhH1zwzLpT33O5o/cj28eAKlfuULs=; h=From:To:Cc:Subject:Date; b=OnyFrDSVJRPo7gRWPKHxPZwrV3tND81cCviSqKHmzwYL3z7OfYrsPXMxlj+OvPdAT kxo0Mc26KOOd4+oUMw8PE2awga6MDhr/2u8t89BEFH6acgtsrj/njOB6rzJoTgN/tI tbB3XYqFnMbfioGfoMvuZgtxL+1khca1BktThPYkImstkRpFqvCG1sXlhKuW1dANOB T52M6R7yAwX7CaPOos6N1qXLh9oOIfZ2JtuPHl/OUzVPYbF5t4NdGvi2Clr/wWGbzW CYwHApHt6BLY1Eq6VDx93qnv6L7X49NbaF0NQpZbo8eqqvROLZ74dHFBrqLKMPvih0 sS++4JpG3JZ4g== 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: [PATCH v8 00/10] tracing/probes: Add more typecast features Date: Wed, 24 Jun 2026 23:41:27 +0900 Message-ID: <178231208703.732967.1160700962651040729.stgit@devnote2> X-Mailer: git-send-email 2.43.0 User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-trace-kernel@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 8th version of series to introduce more typecast features to probe events. The previous version is here: https://lore.kernel.org/all/178217904992.643090.15726197350652241270.stgit@devnote2/ In this version, I removed already picked 2 patches and add 2 new fix and feature patches. The previous BTF typecast patch allows `(STRUCT)FIELD->MEMBER` without $ prefix for eprobes, but it also allows user to use COMM/comm instead of FIELD. $COMM/$comm are special variables, so it should not skip $ prefix[1/10]. However, accessing event fields without $ prefix itself is acceptable, it is generically allowed without typecast[2/10]. Other patches have small fixes according to Julian and Sashiko's comments and are rebased on top of probes/core branch. This series extends BTF typecast feature 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 6. Support event fields without $ prefix on eprobes. Now eprobe events can access its event fields. And added fetcharg dump feature (for debug) and updated test scripts to test part of them. Thanks, --- base-commit: 18dfb4703cd6af27deb30d628dac2e7db2b24e6a Masami Hiramatsu (Google) (10): tracing/probes: Make the $ prefix mandatory for comm access tracing/probes: Allow eprobe to use variable without $ prefix tracing/probes: Support dumping fetcharg program for debugging dynamic events tracing/probes: Support typecast for various probe events tracing/probes: Support nested typecast tracing/probes: Type casting always involves nested calls 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 | 9 Documentation/trace/fprobetrace.rst | 10 Documentation/trace/kprobetrace.rst | 11 kernel/trace/Kconfig | 12 kernel/trace/trace.c | 8 kernel/trace/trace_eprobe.c | 2 kernel/trace/trace_fprobe.c | 2 kernel/trace/trace_kprobe.c | 2 kernel/trace/trace_probe.c | 586 ++++++++++++++++---- kernel/trace/trace_probe.h | 99 ++- kernel/trace/trace_probe_tmpl.h | 25 + kernel/trace/trace_uprobe.c | 3 samples/trace_events/trace-events-sample.c | 40 + samples/trace_events/trace-events-sample.h | 34 + .../ftrace/test.d/dynevent/btf_probe_event.tc | 51 ++ .../test.d/dynevent/eprobes_syntax_errors.tc | 6 .../ftrace/test.d/dynevent/fprobe_syntax_errors.tc | 12 .../ftrace/test.d/kprobe/kprobe_syntax_errors.tc | 12 .../ftrace/test.d/kprobe/uprobe_syntax_errors.tc | 5 19 files changed, 770 insertions(+), 159 deletions(-) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/btf_probe_event.tc -- Masami Hiramatsu (Google)