include rdtsc in the rdrand callback. some systems don't have rdrand yet,

but rdtsc may provide a few bits. ok deraadt

2 files changed, 22 insertions, 26 deletions

diff --git a/sys/arch/amd64/amd64/autoconf.c b/sys/arch/amd64/amd64/autoconf.c
index 5c7566a12c4..f34e557c575 100644
--- a/sys/arch/amd64/amd64/autoconf.c
+++ b/sys/arch/amd64/amd64/autoconf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: autoconf.c,v 1.45 2015/12/27 04:31:34 jsg Exp $	*/
+/*	$OpenBSD: autoconf.c,v 1.46 2016/05/30 17:52:26 tedu Exp $	*/
 /*	$NetBSD: autoconf.c,v 1.1 2003/04/26 18:39:26 fvdl Exp $	*/
 
 /*-
@@ -139,10 +139,8 @@ cpu_configure(void)
 		timeout_set(&viac3_rnd_tmo, viac3_rnd, &viac3_rnd_tmo);
 		viac3_rnd(&viac3_rnd_tmo);
 	}
-	if (has_rdrand || has_rdseed) {
-		timeout_set(&rdrand_tmo, rdrand, &rdrand_tmo);
-		rdrand(&rdrand_tmo);
-	}
+	timeout_set(&rdrand_tmo, rdrand, &rdrand_tmo);
+	rdrand(&rdrand_tmo);
 #ifdef CRYPTO
 	/*
 	 * Also, if the chip has crypto available, enable it.
diff --git a/sys/arch/amd64/amd64/cpu.c b/sys/arch/amd64/amd64/cpu.c
index ea7553acbfd..0cad54c30f6 100644
--- a/sys/arch/amd64/amd64/cpu.c
+++ b/sys/arch/amd64/amd64/cpu.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.c,v 1.98 2016/05/03 08:30:15 kettenis Exp $	*/
+/*	$OpenBSD: cpu.c,v 1.99 2016/05/30 17:52:26 tedu Exp $	*/
 /* $NetBSD: cpu.c,v 1.1 2003/04/26 18:39:26 fvdl Exp $ */
 
 /*-
@@ -879,28 +879,26 @@ rdrand(void *v)
 	union {
 		uint64_t u64;
 		uint32_t u32[2];
-	} r;
+	} r, t;
 	uint8_t valid;
-	int i;
 
-	if (has_rdrand == 0 && has_rdseed == 0)
-		return;
-	for (i = 0; i < 2; i++) {
-		if (has_rdseed)
-			__asm volatile(
-			    "rdseed	%0\n\t"
-			    "setc	%1\n"
-			    : "=r" (r.u64), "=qm" (valid) );
-		if (has_rdseed == 0 || valid == 0)
-			__asm volatile(
-			    "rdrand	%0\n\t"
-			    "setc	%1\n"
-			    : "=r" (r.u64), "=qm" (valid) );
-		if (valid) {
-			add_true_randomness(r.u32[0]);
-			add_true_randomness(r.u32[1]);
-		}
-	}
+	if (has_rdseed)
+		__asm volatile(
+		    "rdseed	%0\n\t"
+		    "setc	%1\n"
+		    : "=r" (r.u64), "=qm" (valid) );
+	if (has_rdrand && (has_rdseed == 0 || valid == 0))
+		__asm volatile(
+		    "rdrand	%0\n\t"
+		    "setc	%1\n"
+		    : "=r" (r.u64), "=qm" (valid) );
+
+	t.u64 = rdtsc();
+
+	if (valid)
+		t.u64 ^= r.u64;
+	add_true_randomness(t.u32[0]);
+	add_true_randomness(t.u32[1]);
 
 	if (tmo)
 		timeout_add_msec(tmo, 10);