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

From: Wang Nan
Date: Wed Aug 26 2015 - 03:41:41 EST


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

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
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

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