v4.19.13 snapshot.
diff --git a/samples/bpf/syscall_nrs.c b/samples/bpf/syscall_nrs.c
new file mode 100644
index 0000000..516e255
--- /dev/null
+++ b/samples/bpf/syscall_nrs.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <uapi/linux/unistd.h>
+#include <linux/kbuild.h>
+
+#define SYSNR(_NR) DEFINE(SYS ## _NR, _NR)
+
+void syscall_defines(void)
+{
+	COMMENT("Linux system call numbers.");
+	SYSNR(__NR_write);
+	SYSNR(__NR_read);
+	SYSNR(__NR_mmap);
+}