Re: [PATCH v10 perf, bpf-next 3/9] perf, bpf: introduce PERF_RECORD_BPF_EVENT
From: Peter Zijlstra <peterz@infradead.org>
Date: 2019-01-17 13:10:00
Also in:
lkml
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?
quoted hunk ↗ jump to hunk
+ * 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) <redacted>