1 files changed, 68 insertions, 0 deletions
diff --git a/random/rndhw.c b/random/rndhw.c
index 775d90f0..cbb28d1a 100644
--- a/random/rndhw.c
+++ b/random/rndhw.c
@@ -1,5 +1,6 @@
 /* rndhw.c  - Access to the external random daemon
  * Copyright (C) 2007  Free Software Foundation, Inc.
+ * Copyright (C) 2012  Dmitry Kasatkin
  *
  * This file is part of Libgcrypt.
  *
@@ -34,6 +35,16 @@
 # endif
 #endif /*ENABLE_PADLOCK_SUPPORT*/
 
+#undef USE_DRNG
+#ifdef ENABLE_DRNG_SUPPORT
+# ifdef HAVE_GCC_ATTRIBUTE_ALIGNED
+#  if (defined (__i386__) && SIZEOF_UNSIGNED_LONG == 4) || defined(__x86_64__)
+#   define USE_DRNG 1
+#  endif
+# endif
+#endif /*ENABLE_RDRAND_SUPPORT*/
+
+typedef void (*add_fn_t)(const void*, size_t, enum random_origins);
 
 /* Keep track on whether the RNG has problems.  */
 static volatile int rng_failed;
@@ -109,6 +120,55 @@ poll_padlock (void (*add)(const void*, size_t, enum random_origins),
 #endif /*USE_PADLOCK*/
 
 
+#ifdef USE_DRNG
+# define RDRAND_RETRY_LOOPS	10
+# define RDRAND_INT	".byte 0x0f,0xc7,0xf0"
+# ifdef __x86_64__
+#  define RDRAND_LONG	".byte 0x48,0x0f,0xc7,0xf0"
+# else
+#  define RDRAND_LONG	RDRAND_INT
+# endif
+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;
+}
+
+
+static inline int
+rdrand_nlong (unsigned long *v, int count)
+{
+  while (count--)
+    if (!rdrand_long(v++))
+      return 0;
+  return 1;
+}
+
+
+static size_t
+poll_drng (add_fn_t add, enum random_origins origin, int fast)
+{
+  volatile char buffer[64] __attribute__ ((aligned (8)));
+  unsigned int nbytes = sizeof (buffer);
+
+  (void)fast;
+
+  if (!rdrand_nlong ((unsigned long *)buffer, sizeof(buffer)/sizeof(long)))
+    return 0;
+  (*add)((void *)buffer, nbytes, origin);
+  return nbytes;
+}
+#endif /*USE_DRNG*/
+
+
 int
 _gcry_rndhw_failed_p (void)
 {
@@ -125,6 +185,10 @@ _gcry_rndhw_poll_fast (void (*add)(const void*, size_t, enum random_origins),
   (void)add;
   (void)origin;
 
+#ifdef USE_DRNG
+  if ((_gcry_get_hw_features () & HWF_INTEL_RDRAND))
+    poll_drng (add, origin, 1);
+#endif
 #ifdef USE_PADLOCK
   if ((_gcry_get_hw_features () & HWF_PADLOCK_RNG))
     poll_padlock (add, origin, 1);
@@ -143,6 +207,10 @@ _gcry_rndhw_poll_slow (void (*add)(const void*, size_t, enum random_origins),
   (void)add;
   (void)origin;
 
+#ifdef USE_DRNG
+  if ((_gcry_get_hw_features () & HWF_INTEL_RDRAND))
+    nbytes += poll_drng (add, origin, 0);
+#endif
 #ifdef USE_PADLOCK
   if ((_gcry_get_hw_features () & HWF_PADLOCK_RNG))
     nbytes += poll_padlock (add, origin, 0);