samples/bpf: add tracepoint support to bpf loader

Recognize "tracepoint/" section name prefix and attach the program
to that tracepoint.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

samples/bpf/bpf_load.c

@@ -49,6 +49,7 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
 	bool is_socket = strncmp(event, "socket", 6) == 0;
 	bool is_kprobe = strncmp(event, "kprobe/", 7) == 0;
 	bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;
+	bool is_tracepoint = strncmp(event, "tracepoint/", 11) == 0;
 	enum bpf_prog_type prog_type;
 	char buf[256];
 	int fd, efd, err, id;
@@ -63,6 +64,8 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
 		prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
 	} else if (is_kprobe || is_kretprobe) {
 		prog_type = BPF_PROG_TYPE_KPROBE;
+	} else if (is_tracepoint) {
+		prog_type = BPF_PROG_TYPE_TRACEPOINT;
 	} else {
 		printf("Unknown event '%s'\n", event);
 		return -1;
@@ -111,12 +114,23 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
 			       event, strerror(errno));
 			return -1;
 		}
-	}
 
 		strcpy(buf, DEBUGFS);
 		strcat(buf, "events/kprobes/");
 		strcat(buf, event);
 		strcat(buf, "/id");
+	} else if (is_tracepoint) {
+		event += 11;
+
+		if (*event == 0) {
+			printf("event name cannot be empty\n");
+			return -1;
+		}
+		strcpy(buf, DEBUGFS);
+		strcat(buf, "events/");
+		strcat(buf, event);
+		strcat(buf, "/id");
+	}
 
 	efd = open(buf, O_RDONLY, 0);
 	if (efd < 0) {
@@ -304,6 +318,7 @@ int load_bpf_file(char *path)
 
 			if (memcmp(shname_prog, "kprobe/", 7) == 0 ||
 			    memcmp(shname_prog, "kretprobe/", 10) == 0 ||
+			    memcmp(shname_prog, "tracepoint/", 11) == 0 ||
 			    memcmp(shname_prog, "socket", 6) == 0)
 				load_and_attach(shname_prog, insns, data_prog->d_size);
 		}
@@ -320,6 +335,7 @@ int load_bpf_file(char *path)
 
 		if (memcmp(shname, "kprobe/", 7) == 0 ||
 		    memcmp(shname, "kretprobe/", 10) == 0 ||
+		    memcmp(shname, "tracepoint/", 11) == 0 ||
 		    memcmp(shname, "socket", 6) == 0)
 			load_and_attach(shname, data->d_buf, data->d_size);
 	}