Index: head/sys/dev/random/ivy.c
===================================================================
--- head/sys/dev/random/ivy.c
+++ head/sys/dev/random/ivy.c
@@ -44,11 +44,13 @@
 
 #include <machine/md_var.h>
 #include <machine/specialreg.h>
+#include <x86/ifunc.h>
 
 #include <dev/random/randomdev.h>
 
 #define	RETRY_COUNT	10
 
+static bool has_rdrand, has_rdseed;
 static u_int random_ivy_read(void *, u_int);
 
 static struct random_source random_ivy = {
@@ -57,10 +59,9 @@
 	.rs_read = random_ivy_read
 };
 
-static inline int
-ivy_rng_store(u_long *buf)
+static int
+x86_rdrand_store(u_long *buf)
 {
-#ifdef __GNUCLIKE_ASM
 	u_long rndval;
 	int retry;
 
@@ -75,11 +76,40 @@
 	    : "+r" (retry), "=r" (rndval) : : "cc");
 	*buf = rndval;
 	return (retry);
-#else /* __GNUCLIKE_ASM */
-	return (0);
-#endif
 }
 
+static int
+x86_rdseed_store(u_long *buf)
+{
+	u_long rndval;
+	int retry;
+
+	retry = RETRY_COUNT;
+	__asm __volatile(
+	    "1:\n\t"
+	    "rdseed	%1\n\t"	/* read randomness into rndval */
+	    "jc		2f\n\t" /* CF is set on success, exit retry loop */
+	    "dec	%0\n\t" /* otherwise, retry-- */
+	    "jne	1b\n\t" /* and loop if retries are not exhausted */
+	    "2:"
+	    : "+r" (retry), "=r" (rndval) : : "cc");
+	*buf = rndval;
+	return (retry);
+}
+
+DEFINE_IFUNC(static, int, x86_rng_store, (u_long *buf), static)
+{
+	has_rdrand = (cpu_feature2 & CPUID2_RDRAND);
+	has_rdseed = (cpu_stdext_feature & CPUID_STDEXT_RDSEED);
+
+	if (has_rdseed)
+		return (x86_rdseed_store);
+	else if (has_rdrand)
+		return (x86_rdrand_store);
+	else
+		return (NULL);
+}
+
 /* It is required that buf length is a multiple of sizeof(u_long). */
 static u_int
 random_ivy_read(void *buf, u_int c)
@@ -90,7 +120,7 @@
 	KASSERT(c % sizeof(*b) == 0, ("partial read %d", c));
 	b = buf;
 	for (count = c; count > 0; count -= sizeof(*b)) {
-		if (ivy_rng_store(&rndval) == 0)
+		if (x86_rng_store(&rndval) == 0)
 			break;
 		*b++ = rndval;
 	}
@@ -104,14 +134,14 @@
 
 	switch (type) {
 	case MOD_LOAD:
-		if (cpu_feature2 & CPUID2_RDRAND) {
+		if (has_rdrand || has_rdseed) {
 			random_source_register(&random_ivy);
 			printf("random: fast provider: \"%s\"\n", random_ivy.rs_ident);
 		}
 		break;
 
 	case MOD_UNLOAD:
-		if (cpu_feature2 & CPUID2_RDRAND)
+		if (has_rdrand || has_rdseed)
 			random_source_deregister(&random_ivy);
 		break;