eal: improve entropy for initial PRNG seed

[dpdk.git] / lib / librte_eal / common / rte_random.c

diff --git a/lib/librte_eal/common/rte_random.c b/lib/librte_eal/common/rte_random.c
index 4d3cf52..e53d96d 100644 (file)
--- a/lib/librte_eal/common/rte_random.c
+++ b/lib/librte_eal/common/rte_random.c
@@ -2,7 +2,11 @@
  * Copyright(c) 2019 Ericsson AB
  */
 
+#ifdef RTE_MACHINE_CPUFLAG_RDSEED
+#include <x86intrin.h>
+#endif
 #include <stdlib.h>
+#include <unistd.h>
 
 #include <rte_branch_prediction.h>
 #include <rte_cycles.h>
@@ -133,7 +137,37 @@ rte_rand(void)
        return __rte_rand_lfsr258(state);
 }
 
+static uint64_t
+__rte_random_initial_seed(void)
+{
+#ifdef RTE_LIBEAL_USE_GETENTROPY
+       int ge_rc;
+       uint64_t ge_seed;
+
+       ge_rc = getentropy(&ge_seed, sizeof(ge_seed));
+
+       if (ge_rc == 0)
+               return ge_seed;
+#endif
+#ifdef RTE_MACHINE_CPUFLAG_RDSEED
+       unsigned int rdseed_rc;
+       unsigned long long rdseed_seed;
+
+       /* first fallback: rdseed instruction, if available */
+       rdseed_rc = _rdseed64_step(&rdseed_seed);
+
+       if (rdseed_rc == 1)
+               return (uint64_t)rdseed_seed;
+#endif
+       /* second fallback: seed using rdtsc */
+       return rte_get_timer_cycles();
+}
+
 RTE_INIT(rte_rand_init)
 {
-       rte_srand(rte_get_timer_cycles());
+       uint64_t seed;
+
+       seed = __rte_random_initial_seed();
+
+       rte_srand(seed);
 }