From: Ross Zwisler <zwisler@google.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
Masami Hiramatsu <mhiramat@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Tom Zanussi <zanussi@kernel.org>,
Zheng Yejian <zhengyejian1@huawei.com>
Subject: Re: [PATCH 1/2] tracing: Add a way to filter function addresses to function names
Date: Mon, 19 Dec 2022 13:57:18 -0700 [thread overview]
Message-ID: <Y6DQLgVYHedPB+F+@google.com> (raw)
In-Reply-To: <20221219183213.916833763@goodmis.org>
On Mon, Dec 19, 2022 at 01:31:07PM -0500, Steven Rostedt wrote:
> From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
>
> There's been several times where an event records a function address in
> its field and I needed to filter on that address for a specific function
> name. It required looking up the function in kallsyms, finding its size,
> and doing a compare of "field >= function_start && field < function_end".
>
> But this would change from boot to boot and is unreliable in scripts.
> Also, it is useful to have this at boot up, where the addresses will not
> be known. For example, on the boot command line:
>
> trace_trigger="initcall_finish.traceoff if func.function == acpi_init"
>
> To implement this, add a ".function" prefix, that will check that the
> field is of size long, and the only operations allowed (so far) are "=="
> and "!=".
>
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Ross Zwisler <zwisler@google.com>
next prev parent reply other threads:[~2022-12-19 20:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-19 18:31 [PATCH 0/2] tracing: Add a way to filter function addresses to function names Steven Rostedt
2022-12-19 18:31 ` [PATCH 1/2] " Steven Rostedt
2022-12-19 20:57 ` Ross Zwisler [this message]
2022-12-19 18:31 ` [PATCH 2/2] tracing/selftests: Add test for event filtering on function name Steven Rostedt
2022-12-19 20:57 ` Ross Zwisler
2022-12-19 22:11 ` Shuah Khan
2022-12-19 22:35 ` Steven Rostedt
2022-12-20 0:20 ` Shuah Khan
2022-12-20 1:21 ` Steven Rostedt
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