linux-kernel - Re: [PATCH] tracing/kprobes: allow to create probe with a module name starting with a digit

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Message-Id: <20170627173830.80e06e87716742a7cc4a6257@kernel.org>
Date:   Tue, 27 Jun 2017 17:38:30 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Sabrina Dubroca <sd@...asysnail.net>
Cc:     linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: Re: [PATCH] tracing/kprobes: allow to create probe with a module
 name starting with a digit

On Thu, 22 Jun 2017 11:24:42 +0200
Sabrina Dubroca <sd@...asysnail.net> wrote:

> Always try to parse an address, since kstrtoul() will safely fail when
> given a symbol as input. If that fails (which will be the case for a
> symbol), try to parse a symbol instead.
> 
> This allows creating a probe such as:
> 
>     p:probe/vlan_gro_receive 8021q:vlan_gro_receive+0
> 
> Which is necessary for this command to work:
> 
>     perf probe -m 8021q -a vlan_gro_receive
> 

Ah, I forgot that case.
Nice catch!

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

Thanks!

> Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
> ---
>  kernel/trace/trace_kprobe.c | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index c129fca6ec99..b53c8d369163 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -707,20 +707,16 @@ static int create_trace_kprobe(int argc, char **argv)
>  		pr_info("Probe point is not specified.\n");
>  		return -EINVAL;
>  	}
> -	if (isdigit(argv[1][0])) {
> -		/* an address specified */
> -		ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
> -		if (ret) {
> -			pr_info("Failed to parse address.\n");
> -			return ret;
> -		}
> -	} else {
> +
> +	/* try to parse an address. if that fails, try to read the
> +	 * input as a symbol. */
> +	if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
>  		/* a symbol specified */
>  		symbol = argv[1];
>  		/* TODO: support .init module functions */
>  		ret = traceprobe_split_symbol_offset(symbol, &offset);
>  		if (ret) {
> -			pr_info("Failed to parse symbol.\n");
> +			pr_info("Failed to parse either an address or a symbol.\n");
>  			return ret;
>  		}
>  		if (offset && is_return &&
> -- 
> 2.13.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>