libc: add wrapper function for 'Genode::cache_coherent()'

Fixes #3858

repos/libports/include/libc/genode.h

@@ -0,0 +1,30 @@
+/*
+ * \brief  POSIX wrappers for important base lib features
+ * \author Christian Prochaska
+ * \date   2020-07-06
+ */
+
+/*
+ * Copyright (C) 2020 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#ifndef _INCLUDE__LIBC__GENODE_H_
+#define _INCLUDE__LIBC__GENODE_H_
+
+/* libc includes */
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void genode_cache_coherent(void *addr, size_t size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _INCLUDE__LIBC__GENODE_H_ */

repos/libports/lib/mk/libc.mk

@@ -18,7 +18,8 @@ SRC_CC = atexit.cc dummies.cc rlimit.cc sysctl.cc \
          pread_pwrite.cc readv_writev.cc poll.cc \
          vfs_plugin.cc dynamic_linker.cc signal.cc \
          socket_operations.cc socket_fs_plugin.cc syscall.cc legacy.cc \
-         getpwent.cc getrandom.cc fork.cc execve.cc kernel.cc component.cc
+         getpwent.cc getrandom.cc fork.cc execve.cc kernel.cc component.cc \
+         genode.cc
 
 #
 # Pthreads

repos/libports/lib/symbols/libc

@@ -237,6 +237,7 @@ fwprintf T
 fwrite T
 fwscanf T
 gai_strerror T
+genode_cache_coherent T
 getaddrinfo T
 getbootfile T
 getbsize T

repos/libports/src/lib/libc/genode.cc

@@ -0,0 +1,23 @@
+/*
+ * \brief  POSIX wrappers for important base lib features
+ * \author Christian Prochaska
+ * \date   2020-07-06
+ */
+
+/*
+ * Copyright (C) 2020 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+/* Genode includes */
+#include <cpu/cache.h>
+
+/* libc includes */
+#include <libc/genode.h>
+
+void genode_cache_coherent(void *addr, size_t size)
+{
+	Genode::cache_coherent((Genode::addr_t)addr, size);
+}