linux-kernel - Re: [PATCH v3 2/6] perf probe: Fix list result when neither dwarf nor map can't find symbol

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Date:	Wed, 26 Aug 2015 19:03:03 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	<acme@...nel.org>, <masami.hiramatsu.pt@...achi.com>,
	<rostedt@...dmis.org>
CC:	<mingo@...hat.com>, <namhyung@...nel.org>, <pi3orama@....com>,
	<lizefan@...wei.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/6] perf probe: Fix list result when neither dwarf
 nor map can't find symbol

Please ignore this one, and use the identical one with shorter title.

Sorry for the noisy.

On 2015/8/26 18:57, Wang Nan wrote:
> 'perf probe -l' reports error if it is unable find symbol through
> address. Here is an example.
>
>   # echo 'p:probe_libc/abs_5 /lib64/libc.so.6:0x5' >
>            /sys/kernel/debug/tracing/uprobe_events
>   # cat /sys/kernel/debug/tracing/uprobe_events
>    p:probe_libc/abs_5 /lib64/libc.so.6:0x0000000000000005
>   # perf probe -l
>     Error: Failed to show event list
>
> Also, this situation triggers a logical inconsistency in
> convert_to_perf_probe_point() that, it returns ENOMEM but actually
> it never try strdup().
>
> This patch removes !tp->module && !is_kprobe condition, so it
> always uses address to build function name if symbol not found.
>
> Test result:
>
>   # perf probe -l
>     probe_libc:abs_5     (on 0x5 in /lib64/libc.so.6)
>
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> ---
>   tools/perf/util/probe-event.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 6c7e538..f7bacbb 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1866,7 +1866,7 @@ static int convert_to_perf_probe_point(struct probe_trace_point *tp,
>   	if (tp->symbol) {
>   		pp->function = strdup(tp->symbol);
>   		pp->offset = tp->offset;
> -	} else if (!tp->module && !is_kprobe) {
> +	} else {
>   		ret = e_snprintf(buf, 128, "0x%" PRIx64, (u64)tp->address);
>   		if (ret < 0)
>   			return ret;


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