kernel: add a syscall to query generic information about an object

libmango/arch/x86_64/syscall.S

@@ -105,6 +105,7 @@ SYSCALL_GATE vm_controller_detach_object SYS_VM_CONTROLLER_DETACH_OBJECT 2
 SYSCALL_GATE vm_controller_supply_pages SYS_VM_CONTROLLER_SUPPLY_PAGES 6
 
 SYSCALL_GATE kern_object_wait SYS_KERN_OBJECT_WAIT 2
+SYSCALL_GATE kern_object_query SYS_KERN_OBJECT_QUERY 2
 
 SYSCALL_GATE futex_wait SYS_FUTEX_WAIT 3
 SYSCALL_GATE futex_wake SYS_FUTEX_WAKE 3

libmango/include-user/mango/object.h

@@ -4,5 +4,8 @@
 #include <mango/types.h>
 
 extern kern_status_t kern_object_wait(kern_wait_item_t *items, size_t nr_items);
+extern kern_status_t kern_object_query(
+	kern_handle_t handle,
+	kern_object_info_t *out);
 
 #endif

libmango/include/mango/syscall.h

@@ -49,5 +49,6 @@
 #define SYS_VM_CONTROLLER_SUPPLY_PAGES  46
 #define SYS_FUTEX_WAIT                  47
 #define SYS_FUTEX_WAKE                  48
+#define SYS_KERN_OBJECT_QUERY           49
 
 #endif

libmango/include/mango/types.h

@@ -109,6 +109,10 @@ typedef unsigned short equeue_packet_type_t;
 
 typedef unsigned int umode_t;
 
+typedef struct {
+	koid_t obj_id;
+} kern_object_info_t;
+
 typedef struct {
 	virt_addr_t io_base;
 	size_t io_len;