Messages in this thread Patch in this message | | | From | Florian Lehner <> | Subject | [FIX bpf,perf] bpf,perf: return EOPNOTSUPP for bpf handler on PERF_COUNT_SW_DUMMY | Date | Mon, 16 Nov 2020 19:37:52 +0100 |
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bpf handlers for perf events other than tracepoints, kprobes or uprobes are attached to the overflow_handler of the perf event.
Perf events of type software/dummy are placeholder events. So when attaching a bpf handle to an overflow_handler of such an event, the bpf handler will not be triggered.
This fix returns the error EOPNOTSUPP to indicate that attaching a bpf handler to a perf event of type software/dummy is not supported.
Signed-off-by: Florian Lehner <dev@der-flo.net> --- kernel/events/core.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kernel/events/core.c b/kernel/events/core.c index da467e1dd49a..4e8846b7ceda 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9668,6 +9668,10 @@ static int perf_event_set_bpf_handler(struct perf_event *event, u32 prog_fd) if (event->prog) return -EEXIST; + if (event->attr.type == PERF_TYPE_SOFTWARE && + event->attr.config == PERF_COUNT_SW_DUMMY) + return -EOPNOTSUPP; + prog = bpf_prog_get_type(prog_fd, BPF_PROG_TYPE_PERF_EVENT); if (IS_ERR(prog)) return PTR_ERR(prog); -- 2.28.0
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