On Tue, Oct 20, 2015 at 08:02:34PM -0700, Alexei Starovoitov wrote:
> +++ b/kernel/trace/bpf_trace.c
> @@ -215,6 +215,50 @@ const struct bpf_func_proto bpf_perf_event_read_proto = {
> .arg2_type = ARG_ANYTHING,
> };
>
> +static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
> +{
> + struct pt_regs *regs = (struct pt_regs *) (long) r1;
> + struct bpf_map *map = (struct bpf_map *) (long) r2;
> + struct bpf_array *array = container_of(map, struct bpf_array, map);
> + void *data = (void *) (long) r4;
> + struct perf_sample_data sample_data;
> + struct perf_event *event;
> + struct perf_raw_record raw = {
> + .size = size,
> + .data = data,
> + };
> +
> + if (unlikely(index >= array->map.max_entries))
> + return -E2BIG;
> +
> + event = (struct perf_event *)array->ptrs[index];
> + if (unlikely(!event))
> + return -ENOENT;
> +
> + if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
> + event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
> + return -EINVAL;
> +
> + if (unlikely(event->oncpu != smp_processor_id()))
> + return -EOPNOTSUPP;
> +
> + perf_sample_data_init(&sample_data, 0, 0);
> + sample_data.raw = &raw;
> + perf_event_output(event, &sample_data, regs);
> + return 0;
> +}
Note that this function also very much requires event to be local.
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