[UNIKRAFT PATCH] lib/syscall_shim: Support system calls without arguments

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

The macros `UK_SYSCALL_DEFINE()`, `UK_SYSCALL_R_DEFINE()`,
`UK_LLSYSCALL_DEFINE()`, and `UK_LLSYSCALL_R_DEFINE()` did not support
defining system calls that do not have input parameters (e.g.,
`getppid`). The definition for empty argument lists was
missing (`UK_ARG_MAP0`).

Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
---
 lib/syscall_shim/include/uk/syscall.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/syscall_shim/include/uk/syscall.h 
b/lib/syscall_shim/include/uk/syscall.h
index a3b79d41..1be4ab91 100644
--- a/lib/syscall_shim/include/uk/syscall.h
+++ b/lib/syscall_shim/include/uk/syscall.h
@@ -93,6 +93,7 @@ typedef long uk_syscall_arg_t;
 #define __UK_NAME2SCALLE_FN(name) UK_CONCAT(uk_syscall_e_, name)
 #define __UK_NAME2SCALLR_FN(name) UK_CONCAT(uk_syscall_r_, name)
 
+#define UK_ARG_MAP0(...)
 #define UK_ARG_MAP1(m, type, arg) m(type, arg)
 #define UK_ARG_MAP2(m, type, arg, ...) m(type, arg), UK_ARG_MAP1(m, 
__VA_ARGS__)
 #define UK_ARG_MAP3(m, type, arg, ...) m(type, arg), UK_ARG_MAP2(m, 
__VA_ARGS__)
-- 
2.20.1