target/ppc: Use qemu_guest_getrandom for DARN

We now have an interface for guest visible random numbers.
Acked-by: NDavid Gibson <david@gibson.dropbear.id.au>
Reviewed-by: NLaurent Vivier <lvivier@redhat.com>
Signed-off-by: NRichard Henderson <richard.henderson@linaro.org>

target/ppc/int_helper.c

@@ -23,6 +23,8 @@
 #include "exec/helper-proto.h"
 #include "crypto/aes.h"
 #include "fpu/softfloat.h"
+#include "qapi/error.h"
+#include "qemu/guest-random.h"
 
 #include "helper_regs.h"
 /*****************************************************************************/
@@ -158,24 +160,37 @@ uint32_t helper_cmpeqb(target_ulong ra, target_ulong rb)
 #undef hasvalue
 
 /*
- * Return invalid random number.
- *
- * FIXME: Add rng backend or other mechanism to get cryptographically suitable
- * random number
+ * Return a random number.
  */
-target_ulong helper_darn32(void)
+uint64_t helper_darn32(void)
 {
-    return -1;
+    Error *err = NULL;
+    uint32_t ret;
+
+    if (qemu_guest_getrandom(&ret, sizeof(ret), &err) < 0) {
+        qemu_log_mask(LOG_UNIMP, "darn: Crypto failure: %s",
+                      error_get_pretty(err));
+        error_free(err);
+        return -1;
+    }
+
+    return ret;
 }
 
-target_ulong helper_darn64(void)
+uint64_t helper_darn64(void)
 {
-    return -1;
-}
+    Error *err = NULL;
+    uint64_t ret;
 
-#endif
+    if (qemu_guest_getrandom(&ret, sizeof(ret), &err) < 0) {
+        qemu_log_mask(LOG_UNIMP, "darn: Crypto failure: %s",
+                      error_get_pretty(err));
+        error_free(err);
+        return -1;
+    }
 
-#if defined(TARGET_PPC64)
+    return ret;
+}
 
 uint64_t helper_bpermd(uint64_t rs, uint64_t rb)
 {