linux-kernel - [RFC PATCH 1/4] Provide linux/set

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Message-Id: <1498717781-29151-1-git-send-email-mpe@ellerman.id.au>
Date:   Thu, 29 Jun 2017 16:29:38 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     kernel-hardening@...ts.openwall.com
Cc:     keescook@...omium.org, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org, labbott@...hat.com
Subject: [RFC PATCH 1/4] 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.

Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
---
 include/linux/set_memory.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 include/linux/set_memory.h

Does this look OK to people? If so it would be great if someone, Kees?,
Andrew?, could pick up patch 1 (it's a nop by itself) and then we can send the
conversions separately later in the merge window?

cheers

diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h
new file mode 100644
index 000000000000..e5140648f638
--- /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_ */
-- 
2.7.4