linux-kernel - Re: [PATCH 2/3] trace/kprobes: allow return probes with offsets and absolute addresses

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Date:   Thu, 16 Feb 2017 08:43:04 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
Cc:     Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] trace/kprobes: allow return probes with offsets and
 absolute addresses

On Wed, 15 Feb 2017 23:47:53 +0530
"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com> wrote:

> Since the kernel includes many non-global functions with same names, we
> will need to use offsets from other symbols (typically _text/_stext) or
> absolute addresses to place return probes on specific functions. Also,
> the core register_kretprobe() API never forbid use of offsets or
> absolute addresses with kretprobes.
> 
> Allow its use with the trace infrastructure.
> 

OK, Looks good to me.

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

Thanks!


> Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
> ---
>  kernel/trace/trace_kprobe.c | 8 --------
>  1 file changed, 8 deletions(-)
> 
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 7ad9e53ad174..2768cb60ebd7 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -679,10 +679,6 @@ static int create_trace_kprobe(int argc, char **argv)
>  		return -EINVAL;
>  	}
>  	if (isdigit(argv[1][0])) {
> -		if (is_return) {
> -			pr_info("Return probe point must be a symbol.\n");
> -			return -EINVAL;
> -		}
>  		/* an address specified */
>  		ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
>  		if (ret) {
> @@ -698,10 +694,6 @@ static int create_trace_kprobe(int argc, char **argv)
>  			pr_info("Failed to parse symbol.\n");
>  			return ret;
>  		}
> -		if (offset && is_return) {
> -			pr_info("Return probe must be used without offset.\n");
> -			return -EINVAL;
> -		}
>  	}
>  	argc -= 2; argv += 2;
>  
> -- 
> 2.11.0
> 


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