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SubjectRe: [PATCH v10 perf, bpf-next 3/9] perf, bpf: introduce PERF_RECORD_BPF_EVENT
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Thanks Peter!

> On Jan 17, 2019, at 5:09 AM, Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, Jan 16, 2019 at 08:29:25AM -0800, Song Liu wrote:
>> + /*
>> + * Record bpf events:
>> + * enum perf_bpf_event_type {
>> + * PERF_BPF_EVENT_UNKNOWN = 0,
>> + * PERF_BPF_EVENT_PROG_LOAD = 1,
>> + * PERF_BPF_EVENT_PROG_UNLOAD = 2,
>> + * };
>> + *
>> + * struct {
>> + * struct perf_event_header header;
>> + * u16 type;
>> + * u16 flags;
>> + * u32 id;
>> + * u8 tag[BPF_TAG_SIZE];
>
> This does forever fix BPF_TAG_SIZE; is that intentional? We could easily
> make that a variable length field like with the other event. Or is that
> value already part of the eBPF ABI?

Yes, BPF_TAG_SIZE is already part of eBPF ABI.

Song

>
>> + * struct sample_id sample_id;
>> + * };
>> + */
>> + PERF_RECORD_BPF_EVENT = 18,
>> @@ -7744,6 +7747,121 @@ void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len, bool unregister,
>> WARN_ONCE(1, "%s: Invalid KSYMBOL type 0x%x\n", __func__, ksym_type);
>> }
>>
>> +struct perf_bpf_event {
>> + struct bpf_prog *prog;
>> + struct {
>> + struct perf_event_header header;
>> + u16 type;
>> + u16 flags;
>> + u32 id;
>> + u8 tag[BPF_TAG_SIZE];
>> + } event_id;
>> +};
>
>> +static void perf_event_bpf_emit_ksymbols(struct bpf_prog *prog,
>> + enum perf_bpf_event_type type)
>> +{
>> + bool unregister = type == PERF_BPF_EVENT_PROG_UNLOAD;
>> + int i;
>> +
>> + if (prog->aux->func_cnt == 0) {
>> + perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF,
>> + (u64)(unsigned long)prog->bpf_func,
>> + prog->jited_len, unregister,
>> + perf_event_bpf_get_name, prog);
>> + } else {
>> + for (i = 0; i < prog->aux->func_cnt; i++) {
>> + struct bpf_prog *subprog = prog->aux->func[i];
>> +
>> + perf_event_ksymbol(
>> + PERF_RECORD_KSYMBOL_TYPE_BPF,
>> + (u64)(unsigned long)subprog->bpf_func,
>> + subprog->jited_len, unregister,
>> + perf_event_bpf_get_name, subprog);
>> + }
>> + }
>> +}
>
> I still think this is a weird place to do this.. :-) See them patches I
> just send.
>
>> +void perf_event_bpf_event(struct bpf_prog *prog,
>> + enum perf_bpf_event_type type,
>> + u16 flags)
>> +{
>> + struct perf_bpf_event bpf_event;
>> +
>> + if (type <= PERF_BPF_EVENT_UNKNOWN ||
>> + type >= PERF_BPF_EVENT_MAX)
>> + return;
>> +
>> + switch (type) {
>> + case PERF_BPF_EVENT_PROG_LOAD:
>> + case PERF_BPF_EVENT_PROG_UNLOAD:
>> + if (atomic_read(&nr_ksymbol_events))
>> + perf_event_bpf_emit_ksymbols(prog, type);
>> + break;
>> + default:
>> + break;
>> + }
>> +
>> + if (!atomic_read(&nr_bpf_events))
>> + return;
>> +
>> + bpf_event = (struct perf_bpf_event){
>> + .prog = prog,
>> + .event_id = {
>> + .header = {
>> + .type = PERF_RECORD_BPF_EVENT,
>> + .size = sizeof(bpf_event.event_id),
>> + },
>> + .type = type,
>> + .flags = flags,
>> + .id = prog->aux->id,
>> + },
>> + };
>
> BUILD_BUG_ON(BPF_TAG_SIZE % sizeof(u64));
>
>> + memcpy(bpf_event.event_id.tag, prog->tag, BPF_TAG_SIZE);
>> + perf_iterate_sb(perf_event_bpf_output, &bpf_event, NULL);
>> +}
>
> Anyway, small nits only:
>
> Acked-by: Peter Zijlstra (Intel) <peterz@infradeaed.org>

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