tracing/filters: Add filter_type to struct ftrace_event_field

The type of a field is stored as a string in @type, and here
we add @filter_type which is an enum value.

This prepares for later patches, so we can specifically assign
different @filter_type for the same @type.

For example normally a "char *" field is treated as a ptr,
but we may want it to be treated as a string when doing filting.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A7B925E.9030605@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 18 insertions, 9 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 300ef788c976..64dda5709cb9 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -755,6 +755,7 @@ struct ftrace_event_field {
         struct list_head        link;
         char                    *name;
         char                    *type;
+        int                     filter_type;
         int                     offset;
         int                     size;
         int                     is_signed;
@@ -800,6 +801,7 @@ extern int apply_subsystem_event_filter(struct event_subsystem *system,
                                         char *filter_string);
 extern void print_subsystem_event_filter(struct event_subsystem *system,
                                          struct trace_seq *s);
+extern int filter_assign_type(const char *type);
 
 static inline int
 filter_check_discard(struct ftrace_event_call *call, void *rec,
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 79d352027a61..5740e90f4ca1 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -44,9 +44,11 @@ int trace_define_field(struct ftrace_event_call *call, const char *type,
         if (!field->type)
                 goto err;
 
+        field->filter_type = filter_assign_type(type);
         field->offset = offset;
         field->size = size;
         field->is_signed = is_signed;
+
         list_add(&field->link, &call->fields);
 
         return 0;
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 490337abed75..22e6d822bbaa 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -476,11 +476,12 @@ static int filter_add_pred_fn(struct filter_parse_state *ps,
 }
 
 enum {
-        FILTER_STATIC_STRING = 1,
-        FILTER_DYN_STRING
+        FILTER_OTHER = 0,
+        FILTER_STATIC_STRING,
+        FILTER_DYN_STRING,
 };
 
-static int is_string_field(const char *type)
+int filter_assign_type(const char *type)
 {
         if (strstr(type, "__data_loc") && strstr(type, "char"))
                 return FILTER_DYN_STRING;
@@ -488,12 +489,18 @@ static int is_string_field(const char *type)
         if (strchr(type, '[') && strstr(type, "char"))
                 return FILTER_STATIC_STRING;
 
-        return 0;
+        return FILTER_OTHER;
+}
+
+static bool is_string_field(struct ftrace_event_field *field)
+{
+        return field->filter_type == FILTER_DYN_STRING ||
+               field->filter_type == FILTER_STATIC_STRING;
 }
 
 static int is_legal_op(struct ftrace_event_field *field, int op)
 {
-        if (is_string_field(field->type) && (op != OP_EQ && op != OP_NE))
+        if (is_string_field(field) && (op != OP_EQ && op != OP_NE))
                 return 0;
 
         return 1;
@@ -550,7 +557,6 @@ static int filter_add_pred(struct filter_parse_state *ps,
         struct ftrace_event_field *field;
         filter_pred_fn_t fn;
         unsigned long long val;
-        int string_type;
         int ret;
 
         pred->fn = filter_pred_none;
@@ -578,9 +584,8 @@ static int filter_add_pred(struct filter_parse_state *ps,
                 return -EINVAL;
         }
 
-        string_type = is_string_field(field->type);
-        if (string_type) {
-                if (string_type == FILTER_STATIC_STRING)
+        if (is_string_field(field)) {
+                if (field->filter_type == FILTER_STATIC_STRING)
                         fn = filter_pred_string;
                 else
                         fn = filter_pred_strloc;