linux-kernel - Re: [PATCH 3/3] perf: revert "perf probe: Fix probing kretprobes"

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Message-Id: <20170216084305.2e03eeab6275a5f1a1443d0d@kernel.org>
Date:   Thu, 16 Feb 2017 08:43:05 +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 3/3] perf: revert "perf probe: Fix probing kretprobes"

On Wed, 15 Feb 2017 23:47:54 +0530
"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com> wrote:

> This reverts commit 25dd9171f51c ("perf probe: Fix probing kretprobes").
> kprobe_events now accepts offsets for kretprobes.
> 
> perf needs to be able to place return probes on static functions that
> have the same name. Using the function name doesn't allow us to do that.
> Instead, we should use the same scheme we use for kprobes: offset'ing
> from _text/_stext.

So now we can use retprobe on static functions safely :)

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

Thanks!


> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
> ---
>  tools/perf/util/probe-event.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 6a6f44dd594b..fa7f81af11e8 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -757,7 +757,7 @@ post_process_kernel_probe_trace_events(struct probe_trace_event *tevs,
>  	}
>  
>  	for (i = 0; i < ntevs; i++) {
> -		if (!tevs[i].point.address || tevs[i].point.retprobe)
> +		if (!tevs[i].point.address)
>  			continue;
>  		/* If we found a wrong one, mark it by NULL symbol */
>  		if (kprobe_warn_out_range(tevs[i].point.symbol,
> @@ -2841,7 +2841,7 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
>  	}
>  
>  	/* Note that the symbols in the kmodule are not relocated */
> -	if (!pev->uprobes && !pp->retprobe && !pev->target) {
> +	if (!pev->uprobes && !pev->target) {
>  		reloc_sym = kernel_get_ref_reloc_sym();
>  		if (!reloc_sym) {
>  			pr_warning("Relocated base symbol is not found!\n");
> -- 
> 2.11.0
> 


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