[PATCH v6 04/13] user_events: Handle matching arguments from dyn_events

Beau Belgrave
2021-12-01T18:25:46Z

Ensures that when dynamic events requests a match with arguments that
they match what is in the user_event.

Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
---
kernel/trace/trace_events_user.c | 77 +++++++++++++++++++++++++++++++-
1 file changed, 76 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
index ad8e0e359eab..04d72e491d02 100644
--- a/kernel/trace/trace_events_user.c
+++ b/kernel/trace/trace_events_user.c
@@ -39,6 +39,7 @@
#define MAX_EVENT_DESC 512
#define EVENT_NAME(user_event) ((user_event)->tracepoint.name)
#define MAX_FIELD_ARRAY_SIZE (2 * PAGE_SIZE)
+#define MAX_FIELD_ARG_NAME 256

static char *register_page_data;

@@ -692,13 +693,87 @@ static int user_event_free(struct dyn_event *ev)
return destroy_user_event(user);
}

+static bool user_field_match(struct ftrace_event_field *field, int argc,
+ const char **argv, int *iout)
+{
+ char *field_name, *arg_name;
+ int len, pos, i = *iout;
+ bool colon = false, match = false;
+
+ if (i >= argc)
+ return false;
+
+ len = MAX_FIELD_ARG_NAME;
+ field_name = kmalloc(len, GFP_KERNEL);
+ arg_name = kmalloc(len, GFP_KERNEL);
+
+ if (!arg_name || !field_name)
+ goto out;
+
+ pos = 0;
+
+ for (; i < argc; ++i) {
+ if (i != *iout)
+ pos += snprintf(arg_name + pos, len - pos, " ");
+
+ pos += snprintf(arg_name + pos, len - pos, argv[i]);
+
+ if (strchr(argv[i], ';')) {
+ ++i;
+ colon = true;
+ break;
+ }
+ }
+
+ pos = 0;
+
+ pos += snprintf(field_name + pos, len - pos, field->type);
+ pos += snprintf(field_name + pos, len - pos, " ");
+ pos += snprintf(field_name + pos, len - pos, field->name);
+
+ if (colon)
+ pos += snprintf(field_name + pos, len - pos, ";");
+
+ *iout = i;
+
+ match = strcmp(arg_name, field_name) == 0;
+out:
+ kfree(arg_name);
+ kfree(field_name);
+
+ return match;
+}
+
+static bool user_fields_match(struct user_event *user, int argc,
+ const char **argv)
+{
+ struct ftrace_event_field *field, *next;
+ struct list_head *head = &user->fields;
+ int i = 0;
+
+ list_for_each_entry_safe_reverse(field, next, head, link)
+ if (!user_field_match(field, argc, argv, &i))
+ return false;
+
+ if (i != argc)
+ return false;
+
+ return true;
+}
+
static bool user_event_match(const char *system, const char *event,
int argc, const char **argv, struct dyn_event *ev)
{
struct user_event *user = container_of(ev, struct user_event, devent);
+ bool match;

- return strcmp(EVENT_NAME(user), event) == 0 &&
+ match = strcmp(EVENT_NAME(user), event) == 0 &&
(!system || strcmp(system, USER_EVENTS_SYSTEM) == 0);
+
+ if (match && argc > 0)
+ match = user_fields_match(user, argc, argv);
+
+ return match;
}

static struct dyn_event_operations user_event_dops = {
--
2.17.1