Tor doesn't use it directly, but the glibc backtrace-to-fd code does
@@ -119,6 +119,7 @@ static int filter_nopar_gen[] = {
SCMP_SYS(stat),
SCMP_SYS(uname),
SCMP_SYS(write),
+ SCMP_SYS(writev),
SCMP_SYS(exit_group),
SCMP_SYS(exit),