tracing: Add hist trigger 'sym' and 'sym-offset' modifiers

Allow users to have address fields displayed as symbols in the output
by appending '.sym' or 'sym-offset' to field names:

   # echo hist:keys=aaa.sym,bbb.sym-offset ... \
              [ if filter] > event/trigger

Link: http://lkml.kernel.org/r/87d4935821491c0275513f0fbfb9bab8d3d3f079.1457029949.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -3855,7 +3855,9 @@ static const char readme_msg[] =
 	"\t    table in its entirety to stdout.  The default format used to\n"
 	"\t    display a given field can be modified by appending any of the\n"
 	"\t    following modifiers to the field name, as applicable:\n\n"
-	"\t            .hex        display a number as a hex value\n\n"
+	"\t            .hex        display a number as a hex value\n"
+	"\t            .sym        display an address as a symbol\n"
+	"\t            .sym-offset display an address as a symbol and offset\n\n"
 	"\t    The 'pause' parameter can be used to pause an existing hist\n"
 	"\t    trigger or to start a hist trigger but not log any events\n"
 	"\t    until told to do so.  'continue' can be used to start or\n"

kernel/trace/trace_events_hist.c

@@ -77,10 +77,12 @@ DEFINE_HIST_FIELD_FN(u8);
 #define HIST_KEY_SIZE_MAX	(MAX_FILTER_STR_VAL + sizeof(u64))
 
 enum hist_field_flags {
-	HIST_FIELD_FL_HITCOUNT	= 1,
-	HIST_FIELD_FL_KEY	= 2,
-	HIST_FIELD_FL_STRING	= 4,
-	HIST_FIELD_FL_HEX	= 8,
+	HIST_FIELD_FL_HITCOUNT		= 1,
+	HIST_FIELD_FL_KEY		= 2,
+	HIST_FIELD_FL_STRING		= 4,
+	HIST_FIELD_FL_HEX		= 8,
+	HIST_FIELD_FL_SYM		= 16,
+	HIST_FIELD_FL_SYM_OFFSET	= 32,
 };
 
 struct hist_trigger_attrs {
@@ -397,6 +399,10 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 	if (field_str) {
 		if (strcmp(field_str, "hex") == 0)
 			flags |= HIST_FIELD_FL_HEX;
+		else if (strcmp(field_str, "sym") == 0)
+			flags |= HIST_FIELD_FL_SYM;
+		else if (strcmp(field_str, "sym-offset") == 0)
+			flags |= HIST_FIELD_FL_SYM_OFFSET;
 		else {
 			ret = -EINVAL;
 			goto out;
@@ -726,6 +732,7 @@ hist_trigger_entry_print(struct seq_file *m,
 			 struct tracing_map_elt *elt)
 {
 	struct hist_field *key_field;
+	char str[KSYM_SYMBOL_LEN];
 	unsigned int i;
 	u64 uval;
 
@@ -741,6 +748,16 @@ hist_trigger_entry_print(struct seq_file *m,
 			uval = *(u64 *)(key + key_field->offset);
 			seq_printf(m, "%s: %llx",
 				   key_field->field->name, uval);
+		} else if (key_field->flags & HIST_FIELD_FL_SYM) {
+			uval = *(u64 *)(key + key_field->offset);
+			sprint_symbol_no_offset(str, uval);
+			seq_printf(m, "%s: [%llx] %-45s",
+				   key_field->field->name, uval, str);
+		} else if (key_field->flags & HIST_FIELD_FL_SYM_OFFSET) {
+			uval = *(u64 *)(key + key_field->offset);
+			sprint_symbol(str, uval);
+			seq_printf(m, "%s: [%llx] %-55s",
+				   key_field->field->name, uval, str);
 		} else if (key_field->flags & HIST_FIELD_FL_STRING) {
 			seq_printf(m, "%s: %-50s", key_field->field->name,
 				   (char *)(key + key_field->offset));
@@ -856,6 +873,10 @@ static const char *get_hist_field_flags(struct hist_field *hist_field)
 
 	if (hist_field->flags & HIST_FIELD_FL_HEX)
 		flags_str = "hex";
+	else if (hist_field->flags & HIST_FIELD_FL_SYM)
+		flags_str = "sym";
+	else if (hist_field->flags & HIST_FIELD_FL_SYM_OFFSET)
+		flags_str = "sym-offset";
 
 	return flags_str;
 }