From 49d859d78c5aeb998b6936fcb5f288f78d713489 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Sun, 31 Jul 2011 14:02:19 -0700
Subject: x86, random: Verify RDRAND functionality and allow it to be disabled

If the CPU declares that RDRAND is available, go through a guranteed
reseed sequence, and make sure that it is actually working (producing
data.)   If it does not, disable the CPU feature flag.

Allow RDRAND to be disabled on the command line (as opposed to at
compile time) for a user who has special requirements with regards to
random numbers.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "Theodore Ts'o" <tytso@mit.edu>
---
 arch/x86/kernel/cpu/common.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'arch/x86/kernel/cpu/common.c')

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 22a073d7fbff..8dbd9294f4f2 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -15,6 +15,7 @@
 #include <asm/stackprotector.h>
 #include <asm/perf_event.h>
 #include <asm/mmu_context.h>
+#include <asm/archrandom.h>
 #include <asm/hypervisor.h>
 #include <asm/processor.h>
 #include <asm/sections.h>
@@ -857,6 +858,7 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
 #endif
 
 	init_hypervisor(c);
+	x86_init_rdrand(c);
 
 	/*
 	 * Clear/Set all flags overriden by options, need do it
-- 
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