linux-kernel - RE: [PATCH v2 4/4] tracing/uprobes: Do not print '0x (null)' when offset is 0

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Date:	Wed, 26 Aug 2015 10:00:40 +0000
From:	平松雅巳 / HIRAMATU，MASAMI 
	<masami.hiramatsu.pt@...achi.com>
To:	"'Wang Nan'" <wangnan0@...wei.com>,
	"acme@...nel.org" <acme@...nel.org>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>
CC:	"mingo@...hat.com" <mingo@...hat.com>,
	"namhyung@...nel.org" <namhyung@...nel.org>,
	"pi3orama@....com" <pi3orama@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	sysp-manager <cti.systems-productivity-manager.ts@...achi.com>
Subject: RE: [PATCH v2 4/4] tracing/uprobes: Do not print '0x  (null)' when
 offset is 0

> From: Wang Nan [mailto:wangnan0@...wei.com]
> 
> When manually added uprobe point with zero address, 'uprobe_events' output
> '(null)' instead of 0x00000000:
> 
>  # echo p:probe_libc/abs_0 /path/to/lib.bin:0x0 arg1=%ax > \
>             /sys/kernel/debug/tracing/uprobe_events
> 
>  # cat /sys/kernel/debug/tracing/uprobe_events
>    p:probe_libc/abs_0 /path/to/lib.bin:0x          (null) arg1=%ax
> 
> This patch fixes this behavior:
> 
>  # cat /sys/kernel/debug/tracing/uprobe_events
>  p:probe_libc/abs_0 /path/to/lib.bin:0x0000000000000000


Looks Good to me :)

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>

Thanks!

> 
> 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>
> ---
>  kernel/trace/trace_uprobe.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index f97479f..d2f6d0b 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -601,7 +601,22 @@ static int probes_seq_show(struct seq_file *m, void *v)
> 
>  	seq_printf(m, "%c:%s/%s", c, tu->tp.call.class->system,
>  			trace_event_name(&tu->tp.call));
> -	seq_printf(m, " %s:0x%p", tu->filename, (void *)tu->offset);
> +	seq_printf(m, " %s:", tu->filename);
> +
> +	/* Don't print "0x  (null)" when offset is 0 */
> +	if (tu->offset) {
> +		seq_printf(m, "0x%p", (void *)tu->offset);
> +	} else {
> +		switch (sizeof(void *)) {
> +		case 4:
> +			seq_printf(m, "0x00000000");
> +			break;
> +		case 8:
> +		default:
> +			seq_printf(m, "0x0000000000000000");
> +			break;
> +		}
> +	}
> 
>  	for (i = 0; i < tu->tp.nr_args; i++)
>  		seq_printf(m, " %s=%s", tu->tp.args[i].name, tu->tp.args[i].comm);
> --
> 1.8.3.4