x86, kaslr: Provide randomness functions

Adds potential sources of randomness: RDRAND, RDTSC, or the i8254.

This moves the pre-alternatives inline rdrand function into the header so
both pieces of code can use it. Availability of RDRAND is then controlled
by CONFIG_ARCH_RANDOM, if someone wants to disable it even for kASLR.

Signed-off-by: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/1381450698-28710-4-git-send-email-keescook@chromium.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 0 insertions, 14 deletions

diff --git a/arch/x86/kernel/cpu/rdrand.c b/arch/x86/kernel/cpu/rdrand.c
index 88db010845cb..384df5105fbc 100644
--- a/arch/x86/kernel/cpu/rdrand.c
+++ b/arch/x86/kernel/cpu/rdrand.c
@@ -31,20 +31,6 @@ static int __init x86_rdrand_setup(char *s)
 }
 __setup("nordrand", x86_rdrand_setup);
 
-/* We can't use arch_get_random_long() here since alternatives haven't run */
-static inline int rdrand_long(unsigned long *v)
-{
-        int ok;
-        asm volatile("1: " RDRAND_LONG "\n\t"
-                     "jc 2f\n\t"
-                     "decl %0\n\t"
-                     "jnz 1b\n\t"
-                     "2:"
-                     : "=r" (ok), "=a" (*v)
-                     : "0" (RDRAND_RETRY_LOOPS));
-        return ok;
-}
-
 /*
  * Force a reseed cycle; we are architecturally guaranteed a reseed
  * after no more than 512 128-bit chunks of random data.  This also