1 /*- 2 * Copyright (c) 2013 The FreeBSD Foundation 3 * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org> 4 * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer 15 * in this position and unchanged. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 * 31 */ 32 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include <sys/param.h> 37 #include <sys/kernel.h> 38 #include <sys/conf.h> 39 #include <sys/lock.h> 40 #include <sys/malloc.h> 41 #include <sys/module.h> 42 #include <sys/random.h> 43 #include <sys/systm.h> 44 45 #include <machine/md_var.h> 46 #include <machine/specialreg.h> 47 48 #include <dev/random/randomdev.h> 49 50 #define RETRY_COUNT 10 51 52 static u_int random_ivy_read(void *, u_int); 53 54 static struct random_source random_ivy = { 55 .rs_ident = "Intel Secure Key RNG", 56 .rs_source = RANDOM_PURE_RDRAND, 57 .rs_read = random_ivy_read 58 }; 59 60 static inline int 61 ivy_rng_store(u_long *buf) 62 { 63 #ifdef __GNUCLIKE_ASM 64 u_long rndval; 65 int retry; 66 67 retry = RETRY_COUNT; 68 __asm __volatile( 69 "1:\n\t" 70 "rdrand %1\n\t" /* read randomness into rndval */ 71 "jc 2f\n\t" /* CF is set on success, exit retry loop */ 72 "dec %0\n\t" /* otherwise, retry-- */ 73 "jne 1b\n\t" /* and loop if retries are not exhausted */ 74 "2:" 75 : "+r" (retry), "=r" (rndval) : : "cc"); 76 *buf = rndval; 77 return (retry); 78 #else /* __GNUCLIKE_ASM */ 79 return (0); 80 #endif 81 } 82 83 /* It is required that buf length is a multiple of sizeof(u_long). */ 84 static u_int 85 random_ivy_read(void *buf, u_int c) 86 { 87 u_long *b, rndval; 88 u_int count; 89 90 KASSERT(c % sizeof(*b) == 0, ("partial read %d", c)); 91 b = buf; 92 for (count = c; count > 0; count -= sizeof(*b)) { 93 if (ivy_rng_store(&rndval) == 0) 94 break; 95 *b++ = rndval; 96 } 97 return (c - count); 98 } 99 100 static int 101 rdrand_modevent(module_t mod, int type, void *unused) 102 { 103 int error = 0; 104 105 switch (type) { 106 case MOD_LOAD: 107 if (cpu_feature2 & CPUID2_RDRAND) { 108 random_source_register(&random_ivy); 109 printf("random: fast provider: \"%s\"\n", random_ivy.rs_ident); 110 } 111 break; 112 113 case MOD_UNLOAD: 114 if (cpu_feature2 & CPUID2_RDRAND) 115 random_source_deregister(&random_ivy); 116 break; 117 118 case MOD_SHUTDOWN: 119 break; 120 121 default: 122 error = EOPNOTSUPP; 123 break; 124 125 } 126 127 return (error); 128 } 129 130 DEV_MODULE(rdrand, rdrand_modevent, NULL); 131 MODULE_VERSION(rdrand, 1); 132 MODULE_DEPEND(rdrand, random_device, 1, 1, 1); 133