---

yaml
---
r: 269541
b: refs/heads/master
c: 628c624
h: refs/heads/master
i:
  269539: af83893
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 63d77173266c1791f1553e9e8ccea65dc87c4485
+refs/heads/master: 628c6246d47b85f5357298601df2444d7f4dd3fd

trunk/arch/x86/Kconfig

@@ -1451,6 +1451,15 @@ config ARCH_USES_PG_UNCACHED
 	def_bool y
 	depends on X86_PAT
 
+config ARCH_RANDOM
+	def_bool y
+	prompt "x86 architectural random number generator" if EXPERT
+	---help---
+	  Enable the x86 architectural RDRAND instruction
+	  (Intel Bull Mountain technology) to generate random numbers.
+	  If supported, this is a high bandwidth, cryptographically
+	  secure hardware random number generator.
+
 config EFI
 	bool "EFI runtime service support"
 	depends on ACPI

trunk/arch/x86/include/asm/archrandom.h

@@ -0,0 +1,73 @@
+/*
+ * This file is part of the Linux kernel.
+ *
+ * Copyright (c) 2011, Intel Corporation
+ * Authors: Fenghua Yu <fenghua.yu@intel.com>,
+ *          H. Peter Anvin <hpa@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef ASM_X86_ARCHRANDOM_H
+#define ASM_X86_ARCHRANDOM_H
+
+#include <asm/processor.h>
+#include <asm/cpufeature.h>
+#include <asm/alternative.h>
+#include <asm/nops.h>
+
+#define RDRAND_RETRY_LOOPS	10
+
+#define RDRAND_INT	".byte 0x0f,0xc7,0xf0"
+#ifdef CONFIG_X86_64
+# define RDRAND_LONG	".byte 0x48,0x0f,0xc7,0xf0"
+#else
+# define RDRAND_LONG	RDRAND_INT
+#endif
+
+#ifdef CONFIG_ARCH_RANDOM
+
+#define GET_RANDOM(name, type, rdrand, nop)			\
+static inline int name(type *v)					\
+{								\
+	int ok;							\
+	alternative_io("movl $0, %0\n\t"			\
+		       nop,					\
+		       "\n1: " rdrand "\n\t"			\
+		       "jc 2f\n\t"				\
+		       "decl %0\n\t"                            \
+		       "jnz 1b\n\t"                             \
+		       "2:",                                    \
+		       X86_FEATURE_RDRAND,                      \
+		       ASM_OUTPUT2("=r" (ok), "=a" (*v)),       \
+		       "0" (RDRAND_RETRY_LOOPS));		\
+	return ok;						\
+}
+
+#ifdef CONFIG_X86_64
+
+GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP5);
+GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP4);
+
+#else
+
+GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP3);
+GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP3);
+
+#endif /* CONFIG_X86_64 */
+
+#endif  /* CONFIG_ARCH_RANDOM */
+
+#endif /* ASM_X86_ARCHRANDOM_H */