From: Steven Rostedt <rostedt@goodmis.org>
To: Douglas Raillard <douglas.raillard@arm.com>
Cc: Steven Rostedt <rostedt@kernel.org>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-perf-users@vger.kernel.org,
Masami Hiramatsu <mhiramat@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Namhyung Kim <namhyung@kernel.org>,
Takaya Saeki <takayas@google.com>,
Tom Zanussi <zanussi@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ian Rogers <irogers@google.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH v3 12/13] tracing: Check for printable characters when printing field dyn strings
Date: Mon, 20 Oct 2025 14:47:32 -0400 [thread overview]
Message-ID: <20251020144732.308326bb@gandalf.local.home> (raw)
In-Reply-To: <8d15e5a6-e80a-4707-a43a-4cbb6d810222@arm.com>
On Mon, 20 Oct 2025 13:19:46 +0100
Douglas Raillard <douglas.raillard@arm.com> wrote:
> Hi Steve,
>
> On 15-10-2025 18:32, Steven Rostedt wrote:
> > From: Steven Rostedt <rostedt@goodmis.org>
> >
> > When the "fields" option is enabled, it prints each trace event field
> > based on its type. But a dynamic array and a dynamic string can both have
> > a "char *" type. Printing it as a string can cause escape characters to be
> > printed and mess up the output of the trace.
>
> We faced the same issue when converting trace.dat to other formats that distinguish
> between a byte buffer and an actual string. The current solution we have is to
> reserve "char []" for actual string and use "u8 []"/"uint8_t []" for byte buffers.
>
> Obviously it does not solve the problem for existing events but that could be worth
> establishing a convention like that for new code and support it in trace_output.c ?
> Most uses of trace data beyond direct printing would require knowing the data schema
> from the header info, so value-based criteria are typically not suitable for that.
Well, what the types are is not quite controlled by me, but by whoever
writes a trace event. Thus, it's not going to be something I can control in trace_output.c
-- Steve
next prev parent reply other threads:[~2025-10-20 18:47 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-15 17:32 [PATCH v3 00/13] tracing: Show contents of syscall trace event user space fields Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 01/13] tracing: Make trace_user_fault_read() exposed to rest of tracing Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 02/13] tracing: Have syscall trace events read user space string Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 03/13] perf: tracing: Simplify perf_sysenter_enable/disable() with guards Steven Rostedt
2025-10-16 11:05 ` kernel test robot
2025-10-15 17:32 ` [PATCH v3 04/13] perf: tracing: Have perf system calls read user space Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 05/13] tracing: Have system call events record user array data Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 06/13] tracing: Display some syscall arrays as strings Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 07/13] tracing: Allow syscall trace events to read more than one user parameter Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 08/13] tracing: Add a config and syscall_user_buf_size file to limit amount written Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 09/13] tracing: Show printable characters in syscall arrays Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 10/13] tracing: Add trace_seq_pop() and seq_buf_pop() Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 11/13] tracing: Add parsing of flags to the sys_enter_openat trace event Steven Rostedt
2025-10-15 17:32 ` [PATCH v3 12/13] tracing: Check for printable characters when printing field dyn strings Steven Rostedt
2025-10-20 12:19 ` Douglas Raillard
2025-10-20 18:47 ` Steven Rostedt [this message]
2025-10-15 17:32 ` [PATCH v3 13/13] tracing: Have persistent ring buffer print syscalls normally Steven Rostedt
2025-10-16 10:33 ` kernel test robot
2025-10-16 11:36 ` kernel test robot
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