Kernel: Use Userspace<> for sys$writev

Kernel/Process.h

@@ -218,7 +218,7 @@ public:
     int sys$close(int fd);
     ssize_t sys$read(int fd, Userspace<u8*>, ssize_t);
     ssize_t sys$write(int fd, const u8*, ssize_t);
-    ssize_t sys$writev(int fd, const struct iovec* iov, int iov_count);
+    ssize_t sys$writev(int fd, Userspace<const struct iovec*> iov, int iov_count);
     int sys$fstat(int fd, Userspace<stat*>);
     int sys$stat(Userspace<const Syscall::SC_stat_params*>);
     int sys$lseek(int fd, off_t, int whence);

Kernel/Syscalls/write.cpp

@@ -30,7 +30,7 @@
 
 namespace Kernel {
 
-ssize_t Process::sys$writev(int fd, const struct iovec* iov, int iov_count)
+ssize_t Process::sys$writev(int fd, Userspace<const struct iovec*> iov, int iov_count)
 {
     REQUIRE_PROMISE(stdio);
     if (iov_count < 0)