bpf: add a testsuite for eBPF maps

. check error conditions and sanity of hash and array map APIs
. check large maps (that kernel gracefully switches to vmalloc from kmalloc)
. check multi-process parallel access and stress test

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/samples/bpf/libbpf.c b/samples/bpf/libbpf.c
index ff65044..17bb520 100644
--- a/samples/bpf/libbpf.c
+++ b/samples/bpf/libbpf.c
@@ -27,12 +27,13 @@
 	return syscall(__NR_bpf, BPF_MAP_CREATE, &attr, sizeof(attr));
 }
 
-int bpf_update_elem(int fd, void *key, void *value)
+int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags)
 {
 	union bpf_attr attr = {
 		.map_fd = fd,
 		.key = ptr_to_u64(key),
 		.value = ptr_to_u64(value),
+		.flags = flags,
 	};
 
 	return syscall(__NR_bpf, BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));