+ return 0;
+}
+
+/*
+ * Create event description
+ */
+static
+int lttng_create_kprobe_event(const char *name, struct lttng_event *event)
+{
+ struct lttng_event_field *field;
+ struct lttng_event_desc *desc;
+ int ret;
+
+ desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
+ if (!desc)
+ return -ENOMEM;
+ desc->name = kstrdup(name, GFP_KERNEL);
+ if (!desc->name) {
+ ret = -ENOMEM;
+ goto error_str;
+ }
+ desc->nr_fields = 1;
+ desc->fields = field =
+ kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
+ if (!field) {
+ ret = -ENOMEM;
+ goto error_field;
+ }
+ field->name = "ip";
+ field->type.atype = atype_integer;
+ field->type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
+ field->type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
+ field->type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
+ field->type.u.basic.integer.reverse_byte_order = 0;
+ field->type.u.basic.integer.base = 16;
+ field->type.u.basic.integer.encoding = lttng_encode_none;
+ desc->owner = THIS_MODULE;
+ event->desc = desc;
+
+ return 0;
+
+error_field:
+ kfree(desc->name);
+error_str:
+ kfree(desc);
+ return ret;
+}
+
+int lttng_kprobes_register(const char *name,
+ const char *symbol_name,
+ uint64_t offset,
+ uint64_t addr,
+ struct lttng_event *event)
+{
+ int ret;
+
+ /* Kprobes expects a NULL symbol name if unused */
+ if (symbol_name[0] == '\0')
+ symbol_name = NULL;
+
+ ret = lttng_create_kprobe_event(name, event);
+ if (ret)
+ goto error;
+ memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
+ event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
+ if (symbol_name) {
+ event->u.kprobe.symbol_name =
+ kzalloc(LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char),
+ GFP_KERNEL);
+ if (!event->u.kprobe.symbol_name) {
+ ret = -ENOMEM;
+ goto name_error;
+ }
+ memcpy(event->u.kprobe.symbol_name, symbol_name,
+ LTTNG_KERNEL_SYM_NAME_LEN * sizeof(char));
+ event->u.kprobe.kp.symbol_name =
+ event->u.kprobe.symbol_name;
+ }
+ event->u.kprobe.kp.offset = offset;
+ event->u.kprobe.kp.addr = (void *) (unsigned long) addr;
+
+ /*
+ * Ensure the memory we just allocated don't trigger page faults.
+ * Well.. kprobes itself puts the page fault handler on the blacklist,
+ * but we can never be too careful.
+ */
+ wrapper_vmalloc_sync_all();
+
+ ret = register_kprobe(&event->u.kprobe.kp);
+ if (ret)
+ goto register_error;
+ return 0;
+
+register_error:
+ kfree(event->u.kprobe.symbol_name);
+name_error:
+ kfree(event->desc->fields);
+ kfree(event->desc->name);
+ kfree(event->desc);
+error:
+ return ret;
+}
+EXPORT_SYMBOL_GPL(lttng_kprobes_register);
+
+void lttng_kprobes_unregister(struct lttng_event *event)
+{
+ unregister_kprobe(&event->u.kprobe.kp);
+}
+EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);
+
+void lttng_kprobes_destroy_private(struct lttng_event *event)
+{
+ kfree(event->u.kprobe.symbol_name);
+ kfree(event->desc->fields);
+ kfree(event->desc->name);
+ kfree(event->desc);