tools lib traceevent: Add support for "%.*s" in bprintk events

The arg notation of '*' in bprintks is not handled by the parser.
Implement it so that they show up properly in the output and do not
kill the tracer from reporting events.

Reported-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-t0ctq7t1xz3ud6wv4v886jou@git.kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

tools/lib/traceevent/event-parse.c

@@ -3370,7 +3370,7 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
 		break;
 	}
 	case PRINT_BSTRING:
-		trace_seq_printf(s, format, arg->string.string);
+		print_str_to_seq(s, format, len_arg, arg->string.string);
 		break;
 	case PRINT_OP:
 		/*
@@ -3471,6 +3471,7 @@ static struct print_arg *make_bprint_args(char *fmt, void *data, int size, struc
 	unsigned long long ip, val;
 	char *ptr;
 	void *bptr;
+	int vsize;
 
 	field = pevent->bprint_buf_field;
 	ip_field = pevent->bprint_ip_field;
@@ -3519,6 +3520,8 @@ static struct print_arg *make_bprint_args(char *fmt, void *data, int size, struc
 				goto process_again;
 			case '0' ... '9':
 				goto process_again;
+			case '.':
+				goto process_again;
 			case 'p':
 				ls = 1;
 				/* fall through */
@@ -3526,23 +3529,29 @@ static struct print_arg *make_bprint_args(char *fmt, void *data, int size, struc
 			case 'u':
 			case 'x':
 			case 'i':
-				/* the pointers are always 4 bytes aligned */
-				bptr = (void *)(((unsigned long)bptr + 3) &
-						~3);
 				switch (ls) {
 				case 0:
-					ls = 4;
+					vsize = 4;
 					break;
 				case 1:
-					ls = pevent->long_size;
+					vsize = pevent->long_size;
 					break;
 				case 2:
-					ls = 8;
+					vsize = 8;
 				default:
+					vsize = ls; /* ? */
 					break;
 				}
-				val = pevent_read_number(pevent, bptr, ls);
-				bptr += ls;
+			/* fall through */
+			case '*':
+				if (*ptr == '*')
+					vsize = 4;
+
+				/* the pointers are always 4 bytes aligned */
+				bptr = (void *)(((unsigned long)bptr + 3) &
+						~3);
+				val = pevent_read_number(pevent, bptr, vsize);
+				bptr += vsize;
 				arg = alloc_arg();
 				arg->next = NULL;
 				arg->type = PRINT_ATOM;
@@ -3550,6 +3559,13 @@ static struct print_arg *make_bprint_args(char *fmt, void *data, int size, struc
 				sprintf(arg->atom.atom, "%lld", val);
 				*next = arg;
 				next = &arg->next;
+				/*
+				 * The '*' case means that an arg is used as the length.
+				 * We need to continue to figure out for what.
+				 */
+				if (*ptr == '*')
+					goto process_again;
+
 				break;
 			case 's':
 				arg = alloc_arg();