user_events: Add basic perf and eBPF support

Adds support to write out user_event data to perf_probe/perf files as
well as to any attached eBPF program.

Link: https://lkml.kernel.org/r/20220118204326.2169-5-beaub@linux.microsoft.com
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index a6794cb1f5862f932f385bd8859564340951a587..371f31472156d2f2720f92de9c39ff2f7502dcf7 100644 (file)
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -551,6 +551,50 @@ static void user_event_ftrace(struct user_event *user, void *data, u32 datalen,
        trace_event_buffer_commit(&event_buffer);
 }
 
+#ifdef CONFIG_PERF_EVENTS
+/*
+ * Writes the user supplied payload out to perf ring buffer or eBPF program.
+ */
+static void user_event_perf(struct user_event *user, void *data, u32 datalen,
+                           void *tpdata)
+{
+       struct hlist_head *perf_head;
+
+       if (bpf_prog_array_valid(&user->call)) {
+               struct user_bpf_context context = {0};
+
+               context.data_len = datalen;
+               context.data_type = USER_BPF_DATA_KERNEL;
+               context.kdata = data;
+
+               trace_call_bpf(&user->call, &context);
+       }
+
+       perf_head = this_cpu_ptr(user->call.perf_events);
+
+       if (perf_head && !hlist_empty(perf_head)) {
+               struct trace_entry *perf_entry;
+               struct pt_regs *regs;
+               size_t size = sizeof(*perf_entry) + datalen;
+               int context;
+
+               perf_entry = perf_trace_buf_alloc(ALIGN(size, 8),
+                                                 &regs, &context);
+
+               if (unlikely(!perf_entry))
+                       return;
+
+               perf_fetch_caller_regs(regs);
+
+               memcpy(perf_entry + 1, data, datalen);
+
+               perf_trace_buf_submit(perf_entry, size, context,
+                                     user->call.event.type, 1, regs,
+                                     perf_head, NULL);
+       }
+}
+#endif
+
 /*
  * Update the register page that is shared between user processes.
  */
@@ -573,6 +617,10 @@ static void update_reg_page_for(struct user_event *user)
 
                                if (probe_func == user_event_ftrace)
                                        status |= EVENT_STATUS_FTRACE;
+#ifdef CONFIG_PERF_EVENTS
+                               else if (probe_func == user_event_perf)
+                                       status |= EVENT_STATUS_PERF;
+#endif
                                else
                                        status |= EVENT_STATUS_OTHER;
                        } while ((++probe_func_ptr)->func);
@@ -612,8 +660,27 @@ static int user_event_reg(struct trace_event_call *call,
                                            data);
                goto dec;
 
-       default:
+#ifdef CONFIG_PERF_EVENTS
+       case TRACE_REG_PERF_REGISTER:
+               ret = tracepoint_probe_register(call->tp,
+                                               call->class->perf_probe,
+                                               data);
+               if (!ret)
+                       goto inc;
+               break;
+
+       case TRACE_REG_PERF_UNREGISTER:
+               tracepoint_probe_unregister(call->tp,
+                                           call->class->perf_probe,
+                                           data);
+               goto dec;
+
+       case TRACE_REG_PERF_OPEN:
+       case TRACE_REG_PERF_CLOSE:
+       case TRACE_REG_PERF_ADD:
+       case TRACE_REG_PERF_DEL:
                break;
+#endif
        }
 
        return ret;
@@ -870,6 +937,9 @@ static int user_event_parse(char *name, char *args, char *flags,
        user->class.get_fields = user_event_get_fields;
        user->class.reg = user_event_reg;
        user->class.probe = user_event_ftrace;
+#ifdef CONFIG_PERF_EVENTS
+       user->class.perf_probe = user_event_perf;
+#endif
 
        mutex_lock(&event_mutex);
        ret = user_event_trace_register(user);