1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright 2020 Conrad Meyer <cem@FreeBSD.org>. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include <sys/cdefs.h> 29 __FBSDID("$FreeBSD$"); 30 31 #include <sys/param.h> 32 #include <sys/kernel.h> 33 #include <sys/pcpu.h> 34 #include <sys/prng.h> 35 #include <sys/smp.h> 36 #include <sys/systm.h> 37 38 #if !PCG_HAS_128BIT_OPS 39 /* On 32-bit platforms, gang together two 32-bit generators. */ 40 typedef struct { 41 pcg32u_random_t states[2]; 42 } pcg64u_random_t; 43 44 static inline void 45 pcg64u_srandom_r(pcg64u_random_t *state64, uint64_t seed) 46 { 47 pcg32u_srandom_r(&state64->states[0], seed); 48 pcg32u_srandom_r(&state64->states[1], seed); 49 } 50 51 static inline uint64_t 52 pcg64u_random_r(pcg64u_random_t *state64) 53 { 54 return ((((uint64_t)pcg32u_random_r(&state64->states[0])) << 32) | 55 pcg32u_random_r(&state64->states[1])); 56 } 57 58 static inline uint64_t 59 pcg64u_boundedrand_r(pcg64u_random_t *state64, uint64_t bound) 60 { 61 uint64_t threshold = -bound % bound; 62 for (;;) { 63 uint64_t r = pcg64u_random_r(state64); 64 if (r >= threshold) 65 return (r % bound); 66 } 67 } 68 #endif 69 70 DPCPU_DEFINE_STATIC(pcg32u_random_t, pcpu_prng32_state); 71 DPCPU_DEFINE_STATIC(pcg64u_random_t, pcpu_prng64_state); 72 73 static void 74 prng_init(void *dummy __unused) 75 { 76 pcg32u_random_t *state; 77 pcg64u_random_t *state64; 78 int i; 79 80 CPU_FOREACH(i) { 81 state = DPCPU_ID_PTR(i, pcpu_prng32_state); 82 pcg32u_srandom_r(state, 1); 83 state64 = DPCPU_ID_PTR(i, pcpu_prng64_state); 84 pcg64u_srandom_r(state64, 1); 85 } 86 } 87 SYSINIT(prng_init, SI_SUB_CPU, SI_ORDER_ANY, prng_init, NULL); 88 89 uint32_t 90 prng32(void) 91 { 92 uint32_t r; 93 94 critical_enter(); 95 r = pcg32u_random_r(DPCPU_PTR(pcpu_prng32_state)); 96 critical_exit(); 97 return (r); 98 } 99 100 uint32_t 101 prng32_bounded(uint32_t bound) 102 { 103 uint32_t r; 104 105 critical_enter(); 106 r = pcg32u_boundedrand_r(DPCPU_PTR(pcpu_prng32_state), bound); 107 critical_exit(); 108 return (r); 109 } 110 111 uint64_t 112 prng64(void) 113 { 114 uint64_t r; 115 116 critical_enter(); 117 r = pcg64u_random_r(DPCPU_PTR(pcpu_prng64_state)); 118 critical_exit(); 119 return (r); 120 } 121 122 uint64_t 123 prng64_bounded(uint64_t bound) 124 { 125 uint64_t r; 126 127 critical_enter(); 128 r = pcg64u_boundedrand_r(DPCPU_PTR(pcpu_prng64_state), bound); 129 critical_exit(); 130 return (r); 131 } 132