Re: [PATCH 5/7] tracing: add config option for print arguments in ftrace

[Zheng Yejian]

On 2024/9/4 14:58, Sven Schnelle wrote:
> Add a config option to disable/enable function argument
> printing support during runtime.
>
> Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
> ---
>   kernel/trace/Kconfig | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
>
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index 721c3b221048..8b9b6cdf39ac 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -242,6 +242,18 @@ config FUNCTION_GRAPH_RETVAL
>   	  enable it via the trace option funcgraph-retval.
>   	  See Documentation/trace/ftrace.rst
>   
> +config FUNCTION_TRACE_ARGS
> +	bool "Kernel Function Tracer Arguments"
> +	depends on HAVE_FUNCTION_ARG_ACCESS_API
> +	depends on DEBUG_INFO_BTF && BPF_SYSCALL

Nice feature!

Just a nit, DEBUG_INFO_BTF currently depends on BPF_SYSCALL,
so BPF_SYSCALL may not be necessary here. This feature
also doesn't seem to depend on bpf.

> +	default n
> +	help
> +	  Support recording and printing of function arguments when using
> +	  the function tracer or function graph tracer. This feature is off
> +	  by default, and can be enabled via the trace option func-args (for
> +	  the function tracer) and funcgraph-args (for the function graph
> +	  tracer).
> +
>   config DYNAMIC_FTRACE
>   	bool "enable/disable function tracing dynamically"
>   	depends on FUNCTION_TRACER

--
Thanks,
Zheng Yejian