provide linux/set_memory.h

Currently code that wants to use set_memory_ro() etc, needs to include
asm/set_memory.h, which doesn't exist on all arches.  Some code knows it
only builds on arches which have the header, other code guards the
inclusion with an #ifdef, neither is ideal.

So create linux/set_memory.h.  This always exists, so users don't need
an #ifdef just to include the header.

When CONFIG_ARCH_HAS_SET_MEMORY=y it includes asm/set_memory.h,
otherwise it provides empty non-failing implementations.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michael Ellerman <[email protected]>
Acked-by: Daniel Borkmann <[email protected]>
Acked-by: Kees Cook <[email protected]>
Acked-by: Laura Abbott <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h
new file mode 100644 (file)
index 0000000..e514064
--- /dev/null
+++ b/include/linux/set_memory.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2017, Michael Ellerman, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation;
+ */
+#ifndef _LINUX_SET_MEMORY_H_
+#define _LINUX_SET_MEMORY_H_
+
+#ifdef CONFIG_ARCH_HAS_SET_MEMORY
+#include <asm/set_memory.h>
+#else
+static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
+static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
+static inline int set_memory_x(unsigned long addr,  int numpages) { return 0; }
+static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
+#endif
+
+#endif /* _LINUX_SET_MEMORY_H_ */