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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/x86/include/asm/smap.h
Initial import
Diffstat (limited to 'arch/x86/include/asm/smap.h')
-rw-r--r--arch/x86/include/asm/smap.h79
1 files changed, 79 insertions, 0 deletions
diff --git a/arch/x86/include/asm/smap.h b/arch/x86/include/asm/smap.h
new file mode 100644
index 000000000..ba665ebd1
--- /dev/null
+++ b/arch/x86/include/asm/smap.h
@@ -0,0 +1,79 @@
+/*
+ * 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 \
+ ALTERNATIVE "", __stringify(__ASM_CLAC), X86_FEATURE_SMAP
+
+#define ASM_STAC \
+ ALTERNATIVE "", __stringify(__ASM_STAC), X86_FEATURE_SMAP
+
+#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("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP);
+}
+
+static __always_inline void stac(void)
+{
+ /* Note: a barrier is implicit in alternative() */
+ alternative("", __stringify(__ASM_STAC), X86_FEATURE_SMAP);
+}
+
+/* These macros can be used in asm() statements */
+#define ASM_CLAC \
+ ALTERNATIVE("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP)
+#define ASM_STAC \
+ ALTERNATIVE("", __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 */