1 files changed, 91 insertions, 0 deletions
diff --git a/arch/x86/include/asm/smap.h b/arch/x86/include/asm/smap.h
new file mode 100644
index 000000000000..8d3120f4e270
--- /dev/null
+++ b/arch/x86/include/asm/smap.h
@@ -0,0 +1,91 @@
+/*
+ * Supervisor Mode Access Prevention support
+ *
+ * Copyright (C) 2012 Intel Corporation
+ * Author: H. Peter Anvin <hpa@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#ifndef _ASM_X86_SMAP_H
+#define _ASM_X86_SMAP_H
+
+#include <linux/stringify.h>
+#include <asm/nops.h>
+#include <asm/cpufeature.h>
+
+/* "Raw" instruction opcodes */
+#define __ASM_CLAC	.byte 0x0f,0x01,0xca
+#define __ASM_STAC	.byte 0x0f,0x01,0xcb
+
+#ifdef __ASSEMBLY__
+
+#include <asm/alternative-asm.h>
+
+#ifdef CONFIG_X86_SMAP
+
+#define ASM_CLAC							\
+	661: ASM_NOP3 ;							\
+	.pushsection .altinstr_replacement, "ax" ;			\
+	662: __ASM_CLAC ;						\
+	.popsection ;							\
+	.pushsection .altinstructions, "a" ;				\
+	altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3 ;	\
+	.popsection
+
+#define ASM_STAC							\
+	661: ASM_NOP3 ;							\
+	.pushsection .altinstr_replacement, "ax" ;			\
+	662: __ASM_STAC ;						\
+	.popsection ;							\
+	.pushsection .altinstructions, "a" ;				\
+	altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3 ;	\
+	.popsection
+
+#else /* CONFIG_X86_SMAP */
+
+#define ASM_CLAC
+#define ASM_STAC
+
+#endif /* CONFIG_X86_SMAP */
+
+#else /* __ASSEMBLY__ */
+
+#include <asm/alternative.h>
+
+#ifdef CONFIG_X86_SMAP
+
+static __always_inline void clac(void)
+{
+	/* Note: a barrier is implicit in alternative() */
+	alternative(ASM_NOP3, __stringify(__ASM_CLAC), X86_FEATURE_SMAP);
+}
+
+static __always_inline void stac(void)
+{
+	/* Note: a barrier is implicit in alternative() */
+	alternative(ASM_NOP3, __stringify(__ASM_STAC), X86_FEATURE_SMAP);
+}
+
+/* These macros can be used in asm() statements */
+#define ASM_CLAC \
+	ALTERNATIVE(ASM_NOP3, __stringify(__ASM_CLAC), X86_FEATURE_SMAP)
+#define ASM_STAC \
+	ALTERNATIVE(ASM_NOP3, __stringify(__ASM_STAC), X86_FEATURE_SMAP)
+
+#else /* CONFIG_X86_SMAP */
+
+static inline void clac(void) { }
+static inline void stac(void) { }
+
+#define ASM_CLAC
+#define ASM_STAC
+
+#endif /* CONFIG_X86_SMAP */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_X86_SMAP_H */