perf trace: Introduce syscall arg formatters

Starting with one for printing pointers in hexadecimal, using the
information in the syscall tracepoint format.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-c4y4jy7qqkn8wsd8q6j1g7zh@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -12,6 +12,11 @@
 #include <libaudit.h>
 #include <stdlib.h>
 
+static size_t syscall_arg__scnprintf_hex(char *bf, size_t size, unsigned long arg)
+{
+	return scnprintf(bf, size, "%#lx", arg);
+}
+
 static struct syscall_fmt {
 	const char *name;
 	const char *alias;
@@ -51,6 +56,7 @@ struct syscall {
 	const char	    *name;
 	bool		    filtered;
 	struct syscall_fmt  *fmt;
+	size_t		    (**arg_scnprintf)(char *bf, size_t size, unsigned long arg);
 };
 
 static size_t fprintf_duration(unsigned long t, FILE *fp)
@@ -207,6 +213,24 @@ static int trace__symbols_init(struct trace *trace, struct perf_evlist *evlist)
 	return err;
 }
 
+static int syscall__set_arg_fmts(struct syscall *sc)
+{
+	struct format_field *field;
+	int idx = 0;
+
+	sc->arg_scnprintf = calloc(sc->tp_format->format.nr_fields - 1, sizeof(void *));
+	if (sc->arg_scnprintf == NULL)
+		return -1;
+
+	for (field = sc->tp_format->format.fields->next; field; field = field->next) {
+		if (field->flags & FIELD_IS_POINTER)
+			sc->arg_scnprintf[idx] = syscall_arg__scnprintf_hex;
+		++idx;
+	}
+
+	return 0;
+}
+
 static int trace__read_syscall_info(struct trace *trace, int id)
 {
 	char tp_name[128];
@@ -259,7 +283,10 @@ static int trace__read_syscall_info(struct trace *trace, int id)
 		sc->tp_format = event_format__new("syscalls", tp_name);
 	}
 
-	return sc->tp_format != NULL ? 0 : -1;
+	if (sc->tp_format == NULL)
+		return -1;
+
+	return syscall__set_arg_fmts(sc);
 }
 
 static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size,
@@ -273,8 +300,14 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size,
 
 		for (field = sc->tp_format->format.fields->next; field; field = field->next) {
 			printed += scnprintf(bf + printed, size - printed,
-					     "%s%s: %ld", printed ? ", " : "",
-					     field->name, args[i++]);
+					     "%s%s: ", printed ? ", " : "", field->name);
+
+			if (sc->arg_scnprintf && sc->arg_scnprintf[i])
+				printed += sc->arg_scnprintf[i](bf + printed, size - printed, args[i]);
+			else
+				printed += scnprintf(bf + printed, size - printed,
+						     "%ld", args[i]);
+                       ++i;
 		}
 	} else {
 		while (i < 6) {