Implement event notifiers for kprobes

[deliverable/lttng-modules.git] / src / probes / lttng-kprobes.c

diff --git a/src/probes/lttng-kprobes.c b/src/probes/lttng-kprobes.c
index 3f9b02356740055f146fcadf6b77004c62e5a096..4e80f1ef62e3acf5ae61c949c8a5af3be7eb4a25 100644 (file)
--- a/src/probes/lttng-kprobes.c
+++ b/src/probes/lttng-kprobes.c
@@ -49,6 +49,20 @@ int lttng_kprobes_event_handler_pre(struct kprobe *p, struct pt_regs *regs)
        return 0;
 }
 
+static
+int lttng_kprobes_event_notifier_handler_pre(struct kprobe *p, struct pt_regs *regs)
+{
+       struct lttng_event_notifier *event_notifier =
+               container_of(p, struct lttng_event_notifier, u.kprobe.kp);
+
+       if (unlikely(!READ_ONCE(event_notifier->enabled)))
+               return 0;
+
+       event_notifier->send_notification(event_notifier);
+
+       return 0;
+}
+
 /*
  * Create event description
  */
@@ -94,6 +108,35 @@ error_str:
        return ret;
 }
 
+/*
+ * Create event_notifier description
+ */
+static
+int lttng_create_kprobe_event_notifier(const char *name, struct lttng_event_notifier *event_notifier)
+{
+       struct lttng_event_desc *desc;
+       int ret;
+
+       desc = kzalloc(sizeof(*event_notifier->desc), GFP_KERNEL);
+       if (!desc)
+               return -ENOMEM;
+       desc->name = kstrdup(name, GFP_KERNEL);
+       if (!desc->name) {
+               ret = -ENOMEM;
+               goto error_str;
+       }
+       desc->nr_fields = 0;
+
+       desc->owner = THIS_MODULE;
+       event_notifier->desc = desc;
+
+       return 0;
+
+error_str:
+       kfree(desc);
+       return ret;
+}
+
 static
 int _lttng_kprobes_register(const char *symbol_name,
                           uint64_t offset,
@@ -127,7 +170,7 @@ int _lttng_kprobes_register(const char *symbol_name,
        lttng_kp->kp.addr = (void *) (unsigned long) addr;
 
        /*
-        * Ensure the memory we just allocated don't trigger page faults.
+        * Ensure the memory we just allocated don't event_notifier page faults.
         * Well.. kprobes itself puts the page fault handler on the blacklist,
         * but we can never be too careful.
         */
@@ -173,12 +216,43 @@ error:
 }
 EXPORT_SYMBOL_GPL(lttng_kprobes_register_event);
 
+int lttng_kprobes_register_event_notifier(const char *symbol_name,
+                          uint64_t offset,
+                          uint64_t addr,
+                          struct lttng_event_notifier *event_notifier)
+{
+       int ret;
+       ret = lttng_create_kprobe_event_notifier(symbol_name, event_notifier);
+       if (ret)
+               goto error;
+
+       ret = _lttng_kprobes_register(symbol_name, offset, addr,
+               &event_notifier->u.kprobe, lttng_kprobes_event_notifier_handler_pre);
+       if (ret)
+               goto register_error;
+
+       return 0;
+
+register_error:
+       kfree(event_notifier->desc->name);
+       kfree(event_notifier->desc);
+error:
+       return ret;
+}
+EXPORT_SYMBOL_GPL(lttng_kprobes_register_event_notifier);
+
 void lttng_kprobes_unregister_event(struct lttng_event *event)
 {
        unregister_kprobe(&event->u.kprobe.kp);
 }
 EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event);
 
+void lttng_kprobes_unregister_event_notifier(struct lttng_event_notifier *event_notifier)
+{
+       unregister_kprobe(&event_notifier->u.kprobe.kp);
+}
+EXPORT_SYMBOL_GPL(lttng_kprobes_unregister_event_notifier);
+
 void lttng_kprobes_destroy_event_private(struct lttng_event *event)
 {
        kfree(event->u.kprobe.symbol_name);
@@ -188,6 +262,14 @@ void lttng_kprobes_destroy_event_private(struct lttng_event *event)
 }
 EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_private);
 
+void lttng_kprobes_destroy_event_notifier_private(struct lttng_event_notifier *event_notifier)
+{
+       kfree(event_notifier->u.kprobe.symbol_name);
+       kfree(event_notifier->desc->name);
+       kfree(event_notifier->desc);
+}
+EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_event_notifier_private);
+
 MODULE_LICENSE("GPL and additional rights");
 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 MODULE_DESCRIPTION("LTTng kprobes probes");