restart_syscall, which can't be called from userspace. However,
the "read" syscall is zero on x86_64. */
int read_syscall = SYS_read;
+#ifdef SYS_pipe
int pipe_syscall = SYS_pipe;
+#else
+int pipe2_syscall = SYS_pipe2;
+#endif
int write_syscall = SYS_write;
int exit_group_syscall = SYS_exit_group;