[PATCH perf/core 08/10] perf probe: Support a special SDT probe format

Masami Hiramatsu
2016-07-12T10:05:54Z

Support a special SDT probe format which can omit the '%' prefix
only if the SDT group name starts with "sdt_". So, for example
both of "%sdt_libc:setjump" and "sdt_libc:setjump" are acceptable
for perf probe --add.

E.g. without this:
----
# perf probe -a sdt_libc:setjmp
Semantic error :There is non-digit char in line number.
...
----
With this:
----
# perf probe -a sdt_libc:setjmp
Added new event:
sdt_libc:setjmp (on %setjmp in /usr/lib64/libc-2.20.so)

You can now use it in all perf tools, such as:

perf record -e sdt_libc:setjmp -aR sleep 1
----

Suggested-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
tools/perf/Documentation/perf-probe.txt | 4 +++-
tools/perf/util/probe-event.c | 12 ++++++++++--
2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 39e3870..736da44 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -152,7 +152,9 @@ Probe points are defined by following syntax.
[[GROUP:]EVENT=]SRC;PTN [ARG ...]

4) Pre-defined SDT events or cached event with name
- %[PROVIDER:]SDTEVENT
+ %[sdt_PROVIDER:]SDTEVENT
+ or,
+ sdt_PROVIDER:SDTEVENT

'EVENT' specifies the name of new event, if omitted, it will be set the name of the probed function. You can also specify a group name by 'GROUP', if omitted, set 'probe' is used for kprobe and 'probe_<bin>' is used for uprobe.
Note that using existing group name can conflict with other events. Especially, using the group name reserved for kernel modules can hide embedded events in the
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 0dadaa3..e12e3b0 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1243,9 +1243,17 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
if (!arg)
return -EINVAL;

- if (arg[0] == '%') {
+ /*
+ * If the probe point starts with '%',
+ * or starts with "sdt_" and has a ':' but no '=',
+ * then it should be a SDT/cached probe point.
+ */
+ if (arg[0] == '%' ||
+ (!strncmp(arg, "sdt_", 4) &&
+ !!strchr(arg, ':') && !strchr(arg, '='))) {
pev->sdt = true;
- arg++;
+ if (arg[0] == '%')
+ arg++;
}

ptr = strpbrk(arg, ";=@+%");