diff --git a/sys/dev/random/ivy.c b/sys/dev/random/ivy.c index 7ab2b0356094..57f3d0a1d80b 100644 --- a/sys/dev/random/ivy.c +++ b/sys/dev/random/ivy.c @@ -44,11 +44,13 @@ __FBSDID("$FreeBSD$"); #include #include +#include #include #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 @@ static struct random_source random_ivy = { .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; @@ -75,9 +76,38 @@ ivy_rng_store(u_long *buf) : "+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). */ @@ -90,7 +120,7 @@ random_ivy_read(void *buf, u_int c) 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 @@ rdrand_modevent(module_t mod, int type, void *unused) 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;