Commit 3207d045 authored by Beau Belgrave's avatar Beau Belgrave Committed by Steven Rostedt (Google)
Browse files

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: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarBeau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 9aed4e15

kernel/trace/trace_events_user.c

+71 −1
Original line number Diff line number Diff line
@@ -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);