1 files changed, 101 insertions, 0 deletions
diff --git a/arch/x86/include/asm/archrandom.h b/arch/x86/include/asm/archrandom.h
new file mode 100644
index 000000000..ebc248e49
--- /dev/null
+++ b/arch/x86/include/asm/archrandom.h
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * This file is part of the Linux kernel.
+ *
+ * Copyright (c) 2011-2014, Intel Corporation
+ * Authors: Fenghua Yu <fenghua.yu@intel.com>,
+ *          H. Peter Anvin <hpa@linux.intel.com>
+ */
+
+#ifndef ASM_X86_ARCHRANDOM_H
+#define ASM_X86_ARCHRANDOM_H
+
+#include <asm/processor.h>
+#include <asm/cpufeature.h>
+
+#define RDRAND_RETRY_LOOPS	10
+
+/* Unconditional execution of RDRAND and RDSEED */
+
+static inline bool __must_check rdrand_long(unsigned long *v)
+{
+	bool ok;
+	unsigned int retry = RDRAND_RETRY_LOOPS;
+	do {
+		asm volatile("rdrand %[out]"
+			     CC_SET(c)
+			     : CC_OUT(c) (ok), [out] "=r" (*v));
+		if (ok)
+			return true;
+	} while (--retry);
+	return false;
+}
+
+static inline bool __must_check rdrand_int(unsigned int *v)
+{
+	bool ok;
+	unsigned int retry = RDRAND_RETRY_LOOPS;
+	do {
+		asm volatile("rdrand %[out]"
+			     CC_SET(c)
+			     : CC_OUT(c) (ok), [out] "=r" (*v));
+		if (ok)
+			return true;
+	} while (--retry);
+	return false;
+}
+
+static inline bool __must_check rdseed_long(unsigned long *v)
+{
+	bool ok;
+	asm volatile("rdseed %[out]"
+		     CC_SET(c)
+		     : CC_OUT(c) (ok), [out] "=r" (*v));
+	return ok;
+}
+
+static inline bool __must_check rdseed_int(unsigned int *v)
+{
+	bool ok;
+	asm volatile("rdseed %[out]"
+		     CC_SET(c)
+		     : CC_OUT(c) (ok), [out] "=r" (*v));
+	return ok;
+}
+
+/*
+ * These are the generic interfaces; they must not be declared if the
+ * stubs in <linux/random.h> are to be invoked,
+ * i.e. CONFIG_ARCH_RANDOM is not defined.
+ */
+#ifdef CONFIG_ARCH_RANDOM
+
+static inline bool __must_check arch_get_random_long(unsigned long *v)
+{
+	return static_cpu_has(X86_FEATURE_RDRAND) ? rdrand_long(v) : false;
+}
+
+static inline bool __must_check arch_get_random_int(unsigned int *v)
+{
+	return static_cpu_has(X86_FEATURE_RDRAND) ? rdrand_int(v) : false;
+}
+
+static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
+{
+	return static_cpu_has(X86_FEATURE_RDSEED) ? rdseed_long(v) : false;
+}
+
+static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
+{
+	return static_cpu_has(X86_FEATURE_RDSEED) ? rdseed_int(v) : false;
+}
+
+extern void x86_init_rdrand(struct cpuinfo_x86 *c);
+
+#else  /* !CONFIG_ARCH_RANDOM */
+
+static inline void x86_init_rdrand(struct cpuinfo_x86 *c) { }
+
+#endif  /* !CONFIG_ARCH_RANDOM */
+
+#endif /* ASM_X86_ARCHRANDOM_H */