[tip: perf/urgent] perf/aux: Disallow aux_output for kernel events

[tip-bot2 for Alexander Shishkin]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     dce5affb94eb54edfff17727a6240a6a5d998666
Gitweb:        https://git.kernel.org/tip/dce5affb94eb54edfff17727a6240a6a5d998666
Author:        Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
AuthorDate:    Wed, 30 Oct 2019 15:47:31 +02:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 13 Nov 2019 08:16:42 +01:00

perf/aux: Disallow aux_output for kernel events

Commit

  ab43762ef0109 ("perf: Allow normal events to output AUX data")

added 'aux_output' bit to the attribute structure, which relies on AUX
events and grouping, neither of which is supported for the kernel events.
This notwithstanding, attempts have been made to use it in the kernel
code, suggesting the necessity of an explicit hard -EINVAL.

Fix this by rejecting attributes with aux_output set for kernel events.

Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Link: https://lkml.kernel.org/r/20191030134731.5437-3-alexander.shishkin@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 kernel/events/core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index e18d8d3..7655441 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11331,6 +11331,13 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
 	struct perf_event *event;
 	int err;
 
+	/*
+	 * Grouping is not supported for kernel events, neither is 'AUX',
+	 * make sure the caller's intentions are adjusted.
+	 */
+	if (attr->aux_output)
+		return ERR_PTR(-EINVAL);
+
 	event = perf_event_alloc(attr, cpu, task, NULL, NULL,
 				 overflow_handler, context, -1);
 	if (IS_ERR(event)) {