samples/bpf, selftests/bpf: Use bpf_probe_read_kernel

A handful of samples and selftests fail to build on s390, because
after commit 0ebeea8ca8 ("bpf: Restrict bpf_probe_read{, str}()
only to archs where they work") bpf_probe_read is not available
anymore.

Fix by using bpf_probe_read_kernel.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200720114806.88823-1-iii@linux.ibm.com

tools/testing/selftests/bpf/progs/bpf_iter_netlink.c

@@ -36,10 +36,10 @@ int dump_netlink(struct bpf_iter__netlink *ctx)
 	if (!nlk->groups)  {
 		group = 0;
 	} else {
-		/* FIXME: temporary use bpf_probe_read here, needs
+		/* FIXME: temporary use bpf_probe_read_kernel here, needs
 		 * verifier support to do direct access.
 		 */
-		bpf_probe_read(&group, sizeof(group), &nlk->groups[0]);
+		bpf_probe_read_kernel(&group, sizeof(group), &nlk->groups[0]);
 	}
 	BPF_SEQ_PRINTF(seq, "%-10u %08x %-8d %-8d %-5d %-8d ",
 		       nlk->portid, (u32)group,
@@ -56,7 +56,7 @@ int dump_netlink(struct bpf_iter__netlink *ctx)
 		 * with current verifier.
 		 */
 		inode = SOCK_INODE(sk);
-		bpf_probe_read(&ino, sizeof(ino), &inode->i_ino);
+		bpf_probe_read_kernel(&ino, sizeof(ino), &inode->i_ino);
 	}
 	BPF_SEQ_PRINTF(seq, "%-8u %-8lu\n", s->sk_drops.counter, ino);
 

tools/testing/selftests/bpf/progs/bpf_iter_tcp4.c

@@ -57,7 +57,7 @@ static long sock_i_ino(const struct sock *sk)
 		return 0;
 
 	inode = &container_of(sk_socket, struct socket_alloc, socket)->vfs_inode;
-	bpf_probe_read(&ino, sizeof(ino), &inode->i_ino);
+	bpf_probe_read_kernel(&ino, sizeof(ino), &inode->i_ino);
 	return ino;
 }
 

tools/testing/selftests/bpf/progs/bpf_iter_tcp6.c

@@ -57,7 +57,7 @@ static long sock_i_ino(const struct sock *sk)
 		return 0;
 
 	inode = &container_of(sk_socket, struct socket_alloc, socket)->vfs_inode;
-	bpf_probe_read(&ino, sizeof(ino), &inode->i_ino);
+	bpf_probe_read_kernel(&ino, sizeof(ino), &inode->i_ino);
 	return ino;
 }
 

tools/testing/selftests/bpf/progs/bpf_iter_udp4.c

@@ -18,7 +18,7 @@ static long sock_i_ino(const struct sock *sk)
 		return 0;
 
 	inode = &container_of(sk_socket, struct socket_alloc, socket)->vfs_inode;
-	bpf_probe_read(&ino, sizeof(ino), &inode->i_ino);
+	bpf_probe_read_kernel(&ino, sizeof(ino), &inode->i_ino);
 	return ino;
 }
 

tools/testing/selftests/bpf/progs/bpf_iter_udp6.c

@@ -25,7 +25,7 @@ static long sock_i_ino(const struct sock *sk)
 		return 0;
 
 	inode = &container_of(sk_socket, struct socket_alloc, socket)->vfs_inode;
-	bpf_probe_read(&ino, sizeof(ino), &inode->i_ino);
+	bpf_probe_read_kernel(&ino, sizeof(ino), &inode->i_ino);
 	return ino;
 }