Well it builds on aarch64, won't on anything else

include/linux/aarch64/syscall.h

@@ -38,8 +38,8 @@
 #define SYS_wait4   260
 // CONSTANT SYS_execve 221
 #define SYS_execve  221
-// CONSTANT SYS_fchmod 52
-#define SYS_fchmod  52
+// CONSTANT SYS_fchmodat 53
+#define SYS_fchmodat 53
 // CONSTANT SYS_faccessat 48
 #define SYS_faccessat 48
 // CONSTANT SYS_brk 234

lib/linux/_open3.c

@@ -26,7 +26,7 @@
 int
 _open3 (char const *file_name, int flags, int mask)
 {
-  int r = _sys_call3 (SYS_open, (long) file_name, (int) flags, (int) mask);
+  int r = _sys_call4 (SYS_openat, (long) -100, (long) file_name, (int) flags, (int) mask);
   if (r > 2)
     {
       __ungetc_clear (r);

lib/linux/access.c

@@ -27,5 +27,5 @@ access (char const *file_name, int how)
 {
   long long_file_name = cast_charp_to_long (file_name);
   long long_how = cast_int_to_long (how);
-  return _sys_call2 (SYS_access, long_file_name, long_how);
+  return _sys_call4 (SYS_faccessat, -100, long_file_name, long_how, 0);
 }

lib/linux/dup2.c

@@ -26,5 +26,5 @@ dup2 (int old, int new)
 {
   long long_old = old;
   long long_new = new;
-  return _sys_call2 (SYS_dup2, long_old, long_new);
+  return _sys_call3 (SYS_dup3, long_old, long_new, 0);
 }

lib/linux/fork.c

@@ -24,5 +24,6 @@
 int
 fork ()
 {
-  return _sys_call (SYS_fork);
+  /* We don't have a _sys_call5 but this works */
+  return _sys_call6 (SYS_clone, 17, 0, 0, 0, 0, 0);
 }

lib/linux/unlink.c

@@ -26,5 +26,5 @@ int
 unlink (char const *file_name)
 {
   long long_file_name = cast_charp_to_long (file_name);
-  return _sys_call1 (SYS_unlink, long_file_name);
+  return _sys_call3 (SYS_unlinkat, -100, long_file_name, 0);
 }

lib/m2/chmod.c

@@ -27,5 +27,5 @@ chmod (char const *file_name, int mask)
 {
   long long_file_name = file_name;
   long long_mask = mask;
-  return _sys_call2 (SYS_chmod, long_file_name, long_mask);
+  return _sys_call2 (SYS_fchmodat, -100, long_file_name, long_mask, 0);
 }

lib/m2/open.c

@@ -27,7 +27,7 @@
 int
 open (char *file_name, int flags, int mask)
 {
-  int r = _sys_call3 (SYS_open, file_name, flags, mask);
+  int r = _sys_call4 (SYS_openat, -100, file_name, flags, mask);
   if (r > 2)
     __ungetc_clear (r);
   return r;