1 /*- 2 * Copyright (c) 2018 Justin Hibbits 3 * Copyright (c) 2013 The FreeBSD Foundation 4 * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org> 5 * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org> 6 * All rights reserved. 7 * 8 * Portions of this software were developed by Konstantin Belousov 9 * under sponsorship from the FreeBSD Foundation. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer 16 * in this position and unchanged. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 * 32 */ 33 34 #include <sys/cdefs.h> 35 #include <sys/param.h> 36 #include <sys/kernel.h> 37 #include <sys/conf.h> 38 #include <sys/lock.h> 39 #include <sys/malloc.h> 40 #include <sys/module.h> 41 #include <sys/random.h> 42 #include <sys/systm.h> 43 44 #include <machine/cpu.h> 45 #include <machine/md_var.h> 46 47 #include <dev/random/randomdev.h> 48 49 /* 50 * Power ISA 3.0 adds a "darn" instruction (Deliver A Random Number). The RNG 51 * backing this instruction conforms to NIST SP800-90B and SP800-90C at the 52 * point of hardware design, and provides a minimum of 0.5 bits of entropy per 53 * bit. 54 */ 55 56 #define RETRY_COUNT 10 57 58 static u_int random_darn_read(void *, u_int); 59 60 static struct random_source random_darn = { 61 .rs_ident = "PowerISA DARN random number generator", 62 .rs_source = RANDOM_PURE_DARN, 63 .rs_read = random_darn_read 64 }; 65 66 static inline int 67 darn_rng_store(u_long *buf) 68 { 69 u_long rndval; 70 int retry; 71 72 for (retry = RETRY_COUNT; retry > 0; --retry) { 73 /* "DARN %rN, 1" instruction */ 74 /* 75 * Arguments for DARN: rN and "L", where "L" can be one of: 76 * 0 - 32-bit conditional random number 77 * 1 - Conditional random number (conditioned to remove bias) 78 * 2 - Raw random number (unprocessed, may include bias) 79 * 3 - Reserved 80 */ 81 __asm __volatile(".long 0x7c0105e6 | (%0 << 21)" : 82 "+r"(rndval)); 83 if (rndval != ~0) 84 break; 85 } 86 87 *buf = rndval; 88 return (retry); 89 } 90 91 /* It is required that buf length is a multiple of sizeof(u_long). */ 92 static u_int 93 random_darn_read(void *buf, u_int c) 94 { 95 u_long *b, rndval; 96 u_int count; 97 98 KASSERT(c % sizeof(*b) == 0, ("partial read %d", c)); 99 b = buf; 100 for (count = c; count > 0; count -= sizeof(*b)) { 101 if (darn_rng_store(&rndval) == 0) 102 break; 103 *b++ = rndval; 104 } 105 return (c - count); 106 } 107 108 static int 109 darn_modevent(module_t mod, int type, void *unused) 110 { 111 int error = 0; 112 113 switch (type) { 114 case MOD_LOAD: 115 if (cpu_features2 & PPC_FEATURE2_DARN) { 116 random_source_register(&random_darn); 117 printf("random: fast provider: \"%s\"\n", random_darn.rs_ident); 118 } 119 break; 120 121 case MOD_UNLOAD: 122 if (cpu_features2 & PPC_FEATURE2_DARN) 123 random_source_deregister(&random_darn); 124 break; 125 126 case MOD_SHUTDOWN: 127 break; 128 129 default: 130 error = EOPNOTSUPP; 131 break; 132 133 } 134 135 return (error); 136 } 137 138 static moduledata_t darn_mod = { 139 "darn", 140 darn_modevent, 141 0 142 }; 143 144 DECLARE_MODULE(darn, darn_mod, SI_SUB_RANDOM, SI_ORDER_FOURTH); 145 MODULE_VERSION(darn, 1); 146 MODULE_DEPEND(darn, random_harvestq, 1, 1, 1); 147