Module Name: src
Committed By: tls
Date: Sat Feb 27 00:43:55 UTC 2016
Modified Files:
src/sys/arch/x86/x86: cpu_rng.c
Log Message:
Add RDSEED and RDRAND backends for cpu_rng on amd64 and i386.
To generate a diff of this commit:
cvs rdiff -u -r1.1 -r1.2 src/sys/arch/x86/x86/cpu_rng.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/x86/x86/cpu_rng.c
diff -u src/sys/arch/x86/x86/cpu_rng.c:1.1 src/sys/arch/x86/x86/cpu_rng.c:1.2
--- src/sys/arch/x86/x86/cpu_rng.c:1.1 Sat Feb 27 00:09:45 2016
+++ src/sys/arch/x86/x86/cpu_rng.c Sat Feb 27 00:43:55 2016
@@ -1,4 +1,4 @@
-/* $NetBSD: cpu_rng.c,v 1.1 2016/02/27 00:09:45 tls Exp $ */
+/* $NetBSD: cpu_rng.c,v 1.2 2016/02/27 00:43:55 tls Exp $ */
/*-
* Copyright (c) 2015 The NetBSD Foundation, Inc.
@@ -42,24 +42,95 @@
static enum {
CPU_RNG_NONE = 0,
CPU_RNG_RDRAND,
- CPU_RNG_RDSEED,
- CPU_RNG_VIA } cpu_rng_mode __read_mostly = CPU_RNG_NONE;
+ CPU_RNG_RDSEED } cpu_rng_mode __read_mostly = CPU_RNG_NONE;
bool
cpu_rng_init(void)
{
+
+ if (cpu_feature[5] & CPUID_SEF_RDSEED) {
+ cpu_rng_mode = CPU_RNG_RDSEED;
+ aprint_normal("cpu_rng: RDSEED\n");
+ return true;
+ } else if (cpu_feature[1] & CPUID2_RDRAND) {
+ cpu_rng_mode = CPU_RNG_RDRAND;
+ aprint_normal("cpu_rng: RDRAND\n");
+ return true;
+ }
return false;
}
+static inline size_t
+cpu_rng_rdrand(cpu_rng_t *out)
+{
+ uint8_t rndsts;
+
+#ifdef __i386__
+ uint32_t lo, hi;
+
+ __asm __volatile("rdrand %0; setc %1" : "=r"(lo), "=qm"(rndsts));
+ if (rndsts != 1)
+ return 0;
+ __asm __volatile("rdrand %0; setc %1" : "=r"(hi), "=qm"(rndsts));
+
+ *out = (uint64_t)lo | ((uint64_t)hi << 32);
+ explicit_memset(&lo, 0, sizeof(lo));
+ explicit_memset(&hi, 0, sizeof(hi));
+ if (rndsts != 1)
+ return sizeof(lo) * NBBY;
+#else
+ __asm __volatile("rdrand %0; setc %1" : "=r"(*out), "=qm"(rndsts));
+ if (rndsts != 1)
+ return 0;
+#endif
+ return sizeof(*out) * NBBY;
+}
+
+static inline size_t
+cpu_rng_rdseed(cpu_rng_t *out)
+{
+ uint8_t rndsts;
+
+#ifdef __i386__
+ uint32_t lo, hi;
+
+ __asm __volatile("rdseed %0; setc %1" : "=r"(lo), "=qm"(rndsts));
+ if (rndsts != 1)
+ goto exhausted;
+ __asm __volatile("rdseed %0; setc %1" : "=r"(hi), "=qm"(rndsts));
+ if (rndsts != 1)
+ goto exhausted;
+
+ *out = (uint64_t)lo | ((uint64_t)hi << 32);
+ explicit_memset(&lo, 0, sizeof(lo));
+ explicit_memset(&hi, 0, sizeof(hi));
+#else
+ __asm __volatile("rdseed %0; setc %1" : "=r"(*out), "=qm"(rndsts));
+#endif
+ if (rndsts != 1)
+ goto exhausted;
+
+ return sizeof(*out) * NBBY;
+
+ /*
+ * Userspace could have exhausted RDSEED, but the
+ * CPU-internal generator feeding RDRAND is guaranteed
+ * to be seeded even in this case.
+ */
+exhausted:
+ return cpu_rng_rdrand(out);
+}
+
size_t
cpu_rng(cpu_rng_t *out)
{
switch (cpu_rng_mode) {
case CPU_RNG_NONE:
+ return 0;
case CPU_RNG_RDSEED:
+ return cpu_rng_rdseed(out);
case CPU_RNG_RDRAND:
- case CPU_RNG_VIA:
- return 0;
+ return cpu_rng_rdrand(out);
default:
panic("cpu_rng: unknown mode %d", (int)cpu_rng_mode);
}
