[PATCH v9 17/22] tracing: Add hist trigger 'syscall' modifier

[Tom Zanussi <tom.zanussi@linux.intel.com>]

Allow users to have syscall id fields displayed as syscall names in
the output by appending '.syscall' to field names:

   # echo hist:keys=aaa.syscall ... \
              [ if filter] > event/trigger

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace.c             |  1 +
 kernel/trace/trace_events_hist.c | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a16ab69..75795e3 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3817,6 +3817,7 @@ static const char readme_msg[] =
 	"\t            .sym        display an address as a symbol\n"
 	"\t            .sym-offset display an address as a symbol and offset\n"
 	"\t            .execname   display a common_pid as a program name\n\n"
+	"\t            .syscall    display a syscall id as a syscall name\n"
 	"\t    By default, the size of the hash table is 2048 entries.  The\n"
 	"\t    'size' param can be used to specify more or fewer than that.\n"
 	"\t    The units are in terms of hashtable entries - if a run uses\n"
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index af1b846..28ccaa1 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -76,6 +76,7 @@ enum hist_field_flags {
 	HIST_FIELD_SYM		= 16,
 	HIST_FIELD_SYM_OFFSET	= 32,
 	HIST_FIELD_EXECNAME	= 64,
+	HIST_FIELD_SYSCALL	= 128,
 };
 
 struct hist_trigger_attrs {
@@ -452,6 +453,8 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 		else if (!strcmp(field_str, "execname") &&
 			 !strcmp(field_name, "common_pid"))
 			flags |= HIST_FIELD_EXECNAME;
+		else if (!strcmp(field_str, "syscall"))
+			flags |= HIST_FIELD_SYSCALL;
 		else {
 			ret = -EINVAL;
 			goto out;
@@ -814,6 +817,16 @@ hist_trigger_entry_print(struct seq_file *m,
 			uval = *(u64 *)(key + key_field->offset);
 			seq_printf(m, "%s: %-16s[%10llu]",
 				   key_field->field->name, comm, uval);
+		} else if (key_field->flags & HIST_FIELD_SYSCALL) {
+			const char *syscall_name;
+
+			uval = *(u64 *)(key + key_field->offset);
+			syscall_name = get_syscall_name(uval);
+			if (!syscall_name)
+				syscall_name = "unknown_syscall";
+
+			seq_printf(m, "%s: %-30s[%3llu]",
+				   key_field->field->name, syscall_name, uval);
 		} else if (key_field->flags & HIST_FIELD_STRING) {
 			seq_printf(m, "%s: %-35s", key_field->field->name,
 				   (char *)(key + key_field->offset));
@@ -929,6 +942,8 @@ static const char *get_hist_field_flags(struct hist_field *hist_field)
 		flags_str = "sym-offset";
 	else if (hist_field->flags & HIST_FIELD_EXECNAME)
 		flags_str = "execname";
+	else if (hist_field->flags & HIST_FIELD_SYSCALL)
+		flags_str = "syscall";
 
 	return flags_str;
 }
-- 
1.9.3