[PATCH 2/5] ftrace perf: Move exclude_kernel tracepoint check to init event

Jiri Olsa
2016-03-16T14:34:53Z

We suppress events with attr::exclude_kernel set when
the event is generated, so following capture will
give no warning but won't produce any data:

$ sudo perf record -e sched:sched_switch:u ls
$ sudo /perf script | wc -l
0

Checking the attr::exclude_(kernel|user) at the event
init time and failing right away for tracepoints from
uprobes/kprobes and native ones:

$ sudo perf record -e sched:sched_switch:u ls
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (sched:sched_switch).
/bin/dmesg may provide additional information.
No CONFIG_PERF_EVENTS=y kernel support configured?

$ sudo perf record -e probe:sys_read:u ls
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (probe:sys_read).
/bin/dmesg may provide additional information.
No CONFIG_PERF_EVENTS=y kernel support configured?

$ ./perf record -e probe_ex:main:k ./ex
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (probe_ex:main).
/bin/dmesg may provide additional information.
No CONFIG_PERF_EVENTS=y kernel support configured?

Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
kernel/events/core.c | 5 -----
kernel/trace/trace_event_perf.c | 25 +++++++++++++++++++++++++
2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index c15fd097af93..ca68fdcf47ce 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6898,11 +6898,6 @@ static int perf_tp_event_match(struct perf_event *event,
{
if (event->hw.state & PERF_HES_STOPPED)
return 0;
- /*
- * All tracepoints are from kernel-space.
- */
- if (event->attr.exclude_kernel)
- return 0;

if (!perf_tp_filter_match(event, data))
return 0;
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index e11108f1d197..6e6d4052f398 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -185,11 +185,36 @@ static void perf_trace_event_close(struct perf_event *p_event)
tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
}

+static int perf_trace_event_attr(struct trace_event_call *tp_event,
+ struct perf_event *event)
+{
+ /*
+ * All tracepoints and kprobes are from kernel-space.
+ */
+ if (((tp_event->flags & TRACE_EVENT_FL_TRACEPOINT) ||
+ (tp_event->flags & TRACE_EVENT_FL_KPROBE)) &&
+ event->attr.exclude_kernel)
+ return -EINVAL;
+
+ /*
+ * All uprobes are from user-space.
+ */
+ if ((tp_event->flags & TRACE_EVENT_FL_UPROBE) &&
+ event->attr.exclude_user)
+ return -EINVAL;
+
+ return 0;
+}
+
static int perf_trace_event_init(struct trace_event_call *tp_event,
struct perf_event *p_event)
{
int ret;

+ ret = perf_trace_event_attr(tp_event, p_event);
+ if (ret)
+ return ret;
+
ret = perf_trace_event_perm(tp_event, p_event);
if (ret)
return ret;
--
2.4.3